.ds OK [\| .ds CK \|] .ds ' \s+4\v@.3m@\'\v@-.3m@\s-4 .ds ` \s+4\v@.3m@\`\v@-.3m@\s-4 .de P .br .. .TH SH 1 .SH NAME ksh \- Korn shell, the not standard command programming language .SH SYNOPSIS .B ksh [ .B \-acefhikmnorstuvx ] [ .B \-o option ] .\|.\|. [ arg .\|.\|. ] .br .SH DESCRIPTION .I ksh\^ is a command programming language that executes commands read from a terminal or a file. .I rsh\^ is a restricted version of the standard command interpreter .IR sh ; it is used to set up login names and execution environments whose capabilities are more controlled than those of the standard shell. See .I Invocation\^ below for the meaning of arguments to the shell. .SS Definitions. A .I metacharacter\^ is one of the following characters: .RS .PP \f3; & ( ) \(bv < > new-line space tab\fP .RE .PP A .I blank\^ is a .B tab or a .BR space . An .I identifier\^ is a sequence of letters, digits, or underscores starting with a letter or underscore. Identifiers are used as names for .IR aliases , .IR functions , and .IR "named parameters" . A .I word\^ is a sequence of .I characters\^ separated by one or more non-quoted .IR metacharacters . .SS Commands. A .I simple-command\^ is a sequence of .I blank\^ separated words which may be preceded by a parameter assignment list. (See .I Environment\^ below). The first word specifies the name of the command to be executed. Except as specified below, the remaining words are passed as arguments to the invoked command. The command name is passed as argument 0 (see .IR exec (2)). The .I value\^ of a simple-command is its exit status if it terminates normally, or (octal) 200+\f2status\^\fP if it terminates abnormally (see .IR signal (2) for a list of status values). .PP A .I pipeline\^ is a sequence of one or more .I commands\^ separated by .BR \(bv . The standard output of each command but the last is connected by a .IR pipe (2) to the standard input of the next command. Each command is run as a separate process; the shell waits for the last command to terminate. The exit status of a pipeline is the exit status of the last command. .PP A .I list\^ is a sequence of one or more pipelines separated by .BR ; , .BR & , .BR && , or .BR \(bv\|\(bv , and optionally terminated by .BR ; , .BR & , or .BR \(bv& . Of these five symbols, .BR ; , .BR & , and .BR \(bv& have equal precedence, which is lower than that of .B && and .BR \(bv\|\(bv . The symbols .B && and .B \(bv\|\(bv also have equal precedence. A semicolon .RB ( ; ) causes sequential execution of the preceding pipeline; an ampersand .RB ( & ) causes asynchronous execution of the preceding pipeline (i.e., the shell does .I not\^ wait for that pipeline to finish). The symbol .B \(bv& causes asynchronous execution of the preceding command or pipeline with a two-way pipe established to the parent shell. The standard input and output of the spawned command can be written to and read from by the parent Shell using the .B \-p option of the special commands .B read and .B print\^ described later. Only one such command can be active at any given time. The symbol .B && .RB (\| \(bv\|\(bv \^) causes the .I list\^ following it to be executed only if the preceding pipeline returns a zero (non-zero) value. An arbitrary number of new-lines may appear in a .I list,\^ instead of semicolons, to delimit commands. .PP A .I command\^ is either a simple-command or one of the following. Unless otherwise stated, the value returned by a command is that of the last simple-command executed in the command. .TP \f3for\fP \f2identifier\^\fP \*(OK \f3in\fP \f2word\^\fP .\|.\|. \*(CK \f3do\fP \f2list\^\fP \f3done\fP Each time a .B for command is executed, .I identifier\^ is set to the next .I word\^ taken from the .B in .I word\^ list. If .BI in " word\^" \&.\|.\|. is omitted, then the .B for command executes the \f3do\fP \f2list\^\fP once for each positional parameter that is set (see .I "Parameter Substitution\^" below). Execution ends when there are no more words in the list. .TP \f3select\fP \f2identifier\^\fP \*(OK \f3in\fP \f2word\^\fP .\|.\|. \*(CK \f3do\fP \f2list\^\fP \f3done\fP A .B select command prints on standard error (file descriptor 2), the set of .IR word s, each preceded by a number. If .BI in " word\^" \&.\|.\|. is omitted, then the positional parameters are used instead (see .I "Parameter Substitution\^" below). The .SM .B PS3 prompt is printed and a line is read from the standard input. If this line consists of the number of one of the listed .BR word s, then the value of the parameter .I identifier\^ is set to the .I word\^ corresponding to this number. If this line is empty the selection list is printed again. Otherwise the value of the parameter .I identifier\^ is set to .BR null . The contents of the line read from standard input is saved in the parameter .SM .BR REPLY. The .I list\^ is executed for each selection until a .B break\^ or .I end-of-file\^ is encountered. .TP \f3case\fP \f2word\^\fP \f3in\fP \*(OK \f2pattern\^\fP \*(OK \(bv \ \f2pattern\^\fP \*(CK .\|.\|. \f3)\fP \f2list\^\fP \f3;;\fP \*(CK .\|.\|. \f3esac\fP A .B case command executes the .I list\^ associated with the first .I pattern\^ that matches .IR word . The form of the patterns is the same as that used for file-name generation (see .I "File Name Generation\^" below). .TP \f3if\fP \f2list\^\fP \f3then\fP \f2list\^\fP \*(OK \ \f3elif\fP \f2list\^\fP \f3then\fP \f2list\^\fP \*(CK .\|.\|. \ \*(OK \f3else\fP \f2list\^\fP \*(CK \f3f\&i\fP The .I list\^ following \f3if\fP is executed and, if it returns a zero exit status, the .I list\^ following the first .B then is executed. Otherwise, the .I list\^ following \f3elif\fP is executed and, if its value is zero, the .I list\^ following the next .B then is executed. Failing that, the .B else .I list\^ is executed. If no .B else .I list\^ or .B then .I list\^ is executed, then the .B if command returns a zero exit status. .TP .PD 0 \f3while\fP \f2list\^\fP \f3do\fP \f2list\^\fP \f3done\fP .TP \f3until\fP \f2list\^\fP \f3do\fP \f2list\^\fP \f3done\fP .PD A .B while command repeatedly executes the .B while .I list\^ and, if the exit status of the last command in the list is zero, executes the .B do .IR list ; otherwise the loop terminates. If no commands in the .B do .I list\^ are executed, then the .B while command returns a zero exit status; .B until may be used in place of .B while to negate the loop termination test. .TP \f3(\fP\f2list\^\fP\f3)\fP .br Execute .I list\^ in a separate environment. Note, that if two adjacent open parentheses are needed for nesting, a space must be inserted to avoid arithmetic evaluation as described below. .TP \f3{ \fP\f2list\^\fP\f3;}\fP .br .I list\^ is simply executed. Note that .B { is a .I keyword\^ and requires a blank in order to be recognized. .TP .PD 0 \f3function\fP \f2identifier\^\fP \f3{\fP \f2list\^\fP \f3;}\fP .TP \f2identifier\^\fP \f3() {\fP \f2list\^\fP \f3;}\fP .PD Define a function which is referenced by .IR identifier . The body of the function is the .I list\^ of commands between .B { and .BR } . (See .I Functions\^ below). .TP \f3time \fP\f2pipeline\^\fP .br The .I pipeline\^ is executed and the elapsed time as well as the user and system time are printed on standard error. .PP The following keywords are only recognized as the first word of a command and when not quoted: .if t .RS .PP .B .if n if then else elif fi case esac for while until do done { } function select time .if t if then else elif fi case esac for while until do done { } function select time .if t .RE .SS Comments. A word beginning with .B # causes that word and all the following characters up to a new-line to be ignored. .SS Aliasing. The first word of each command is replaced by the text of an .B alias if an .B alias for this word has been defined. The first character of an .B alias name can be any printable character, but the rest of the characters must be the same as for a valid .IR identifier . The replacement string can contain any valid Shell script including the metacharacters listed above. The first word of each command of the replaced text will not be tested for additional aliases. If the last character of the alias value is a .I blank\^ then the word following the alias will also be checked for alias substitution. Aliases can be used to redefine special builtin commands but cannot be used to redefine the keywords listed above. Aliases can be created, listed, and exported with the .B alias command and can be removed with the .B unalias command. Exported aliases remain in effect for sub-shells but must be reinitialized for separate invocations of the Shell (See .I Invocation\^ below). .PP .I Aliasing\^ is performed when scripts are read, not while they are executed. Therefore, for an alias to take effect the .B alias command has to be executed before the command which references the alias is read. .PP Aliases are frequently used as a short hand for full path names. An option to the aliasing facility allows the value of the alias to be automatically set to the full pathname of the corresponding command. These aliases are called .I tracked aliases. The value of a .I tracked alias is defined the first time the identifier is read and becomes undefined each time the .SM .B PATH variable is reset. These aliases remain .I tracked so that the next subsequent reference will redefine the value. Several tracked aliases are compiled into the shell. The .B \-h option of the .B set command makes each command name which is an .I identifier\^ into a tracked alias. .PP The following .I exported aliases are compiled into the shell but can be unset or redefined: .RS 20 .PD 0 .TP .B "echo=\(fmprint \-\(fm" .TP .B "false=\(fmlet 0\(fm" .TP .B "functions=\(fmtypeset \-f\(fm" .TP .B "history=\(fmfc \-l\(fm" .TP .B "integer=\(fmtypeset \-i\(fm" .TP .B "nohup=\(fmnohup \(fm" .TP .B "pwd=\(fmprint \- $\s-1PWD\s+1\(fm" .TP .B "r=\(fmfc \-e \-\(fm" .TP .B "true=\(fm:\(fm" .TP .B "type=\(fmwhence \-v\(fm" .TP .B "hash=\(fmalias \-t\(fm" .PD .RE .SS Tilde Substitution. After alias substitution is performed, each word is checked to see if it begins with an unquoted .BR \(ap . If it does, then the word up to a .B / is checked to see if it matches a user name in the .B /etc/passwd file. If a match is found, the .B \(ap and the matched login name is replaced by the login directory of the matched user. This is called a .I tilde substitution. If no match is found, the original text is left unchanged. A .B \(ap by itself, or in front of a .BR / , is replaced by the value of the .B .SM HOME parameter. A .B \(ap followed by a .B + or .B \- is replaced by the value of the parameter .B .SM PWD and .B .SM OLDPWD respectively. .PP In addition, the value of each .I "keyword parameter" is checked to see if it begins with a .B \(ap or if a .B \(ap appears after a .BR : . In either of these cases a .I tilde substitution is attempted. .SS Command Substitution. The standard output from a command enclosed in a pair of grave accents (\^\f3\*`\^\*`\fP\^) may be used as part or all of a word; trailing new-lines are removed. The command substitution \^\f3\*`\^cat file\^\*`\fP\^ can be replaced by the equivalent but faster \^\f3\*`\^ \|" ''. .TP .SM .B PS3 Selection prompt string used within a .B select loop, by default .RB `` "#? \|" ''. .TP .SM .B SHELL The pathname of the .I shell\^ is kept in the environment. At invocation, if the value of this variable contains an .B r in the basename, then the shell becomes restricted. .TP .B .SM TMOUT If set to a value greater than zero, the shell will terminate if a command is not entered within the prescribed number of seconds. (Note that the shell can be compiled with a maximum bound for this value which cannot be exceeded.) .TP .B .SM VISUAL If the value of this variable ends in .IR emacs , .IR gmacs , or .I vi then the corresponding option (see Special Command .B set below) will be turned on. .PD .RE .PP The shell gives default values to \f3\s-1PATH\s+1\fP, \f3\s-1PS1\s+1\fP, \f3\s-1PS2\s+1\fP, \f3\s-1MAILCHECK\s+1\fP, \f3\s-1TMOUT\s+1\fP and \f3\s-1IFS\s+1\fP, while .SM .BR HOME , .SM .B SHELL .SM .B ENV and .SM .B MAIL are not set at all by the shell (although .SM .B HOME .I is\^ set by .IR login (1)). On some systems .SM .B MAIL and .SM .B SHELL are also set by .IR login (1)). .SS Blank Interpretation. After parameter and command substitution, the results of substitutions are scanned for the field separator characters ( those found in .SM .B IFS ) and split into distinct arguments where such characters are found. Explicit null arguments (\^\f3"\^"\fP or \f3\*\(fm\^\*\(fm\fP\^) are retained. Implicit null arguments (those resulting from .I parameters\^ that have no values) are removed. .SS File Name Generation. Following substitution, each command .I word\^ is scanned for the characters .BR \(** , .BR ? , and .B \*(OK\^ unless the .B \-f option has been .BR set . If one of these characters appears then the word is regarded as a .IR pattern . The word is replaced with alphabetically sorted file names that match the pattern. If no file name is found that matches the pattern, then the word is left unchanged. When a .I pattern\^ is used for file name generation, the character .B . at the start of a file name or immediately following a .BR / , as well as the character .B / itself, must be matched explicitly. In other instances of pattern matching the .B / and .B . are not treated specially. .PP .PD 0 .RS .TP .B \(** Matches any string, including the null string. .TP .B ? Matches any single character. .TP .BR \*(OK \^.\|.\|.\^ \*(CK Matches any one of the enclosed characters. A pair of characters separated by .B \- matches any character lexically between the pair, inclusive. If the first character following the opening "[ \|" is a "! \|" then any character not enclosed is matched. A .B \- can be included in the character set by putting it as the first or last character. .PD .RE .SS Quoting. Each of the .I metacharacters\^ listed above (See .I Definitions above). has a special meaning to the shell and cause termination of a word unless quoted. A character may be .I quoted\^ (i.e., made to stand for itself) by preceding it with a .BR \e . The pair .B \enew-line is ignored. All characters enclosed between a pair of single quote marks (\^\f3\(fm\^\(fm\fP\^), except a single quote, are quoted. Inside double quote marks (\f3"\^"\fP), parameter and command substitution occurs and .B \e quotes the characters .BR \e , .BR \(fm , \f3"\fP, and .BR $ . .B "$\(**" is equivalent to \f3"$1 \|$2\fP \|.\|.\|.\f3"\fP, whereas .B "$@" is equivalent to .B "$1"\| .B "$2"\| \&.\|.\|.\^. .PP The special meaning of keywords can be removed by quoting any character of the keyword. The recognition of special command names listed below cannot be altered by quoting them. .SS Arithmetic Evaluation. An ability to perform integer arithmetic is provided with the special command .BR let . Evaluations are performed using .I long\^ arithmetic. Constants are of the form \*(OK\f2base\f3#\^\f1\*(CK\f2n\^\fP where .I base\^ is a decimal number between two and thirty-six representing the arithmetic base and .I n\^ is a number in that base. If .I base\^ is omitted then base 10 is used. .PP An internal integer representation of a .I named parameter\^ can be specified with the .B \-i option of the .B typeset special command. When this attribute is selected the first assignment to the parameter determines the arithmetic base to be used when parameter substitution occurs. .PP Since many of the arithmetic operators require quoting, an alternative form of the .B let command is provided. For any command which begins with a .BR (( , all the characters until a matching .B )) are treated as a quoted expression. More precisely, .B (( \&.\|.\|. .B )) is equivalent to .B let\^ \f3"\fP \|.\|.\|.\f3"\fP. .SS Prompting. When used interactively, the shell prompts with the value of .SM .B PS1 before reading a command. If at any time a new-line is typed and further input is needed to complete a command, then the secondary prompt (i.e., the value of .BR \s-1PS2\s+1 ) is issued. .SS Input/Output. Before a command is executed, its input and output may be redirected using a special notation interpreted by the shell. The following may appear anywhere in a simple-command or may precede or follow a .I command\^ and are .I not\^ passed on to the invoked command. Command and parameter substitution occurs before .I word\^ or .I digit\^ is used except as noted below. File name generation occurs only if the pattern matches a single file and blank interpretation is not performed. .TP 14 .BI < word Use file .I word\^ as standard input (file descriptor 0). .TP .BI > word Use file .I word\^ as standard output (file descriptor 1). If the file does not exist then it is created; otherwise, it is truncated to zero length. .TP .BI >\h@-.3m@> word Use file .I word\^ as standard output. If the file exists then output is appended to it (by first seeking to the end-of-file); otherwise, the file is created. .TP \f3<\h@-.3m@<\fP\*(OK\f3\-\fP\*(CK\f2word\fP The shell input is read up to a line that is the same as .IR word , or to an end-of-file. No parameter substitution, command substitution or file name generation is performed on .IR word . The resulting document, called a .IR here-document , becomes the standard input. If any character of .I word\^ is quoted, then no interpretation is placed upon the characters of the document; otherwise, parameter and command substitution occurs, .B \enew-line is ignored, and .B \e must be used to quote the characters .BR \e , .BR $ , .BR \*` , and the first character of .IR word . If .B \- is appended to .BR <\h@-.3m@< , then all leading tabs are stripped from .I word\^ and from the document. .TP .BI <& digit The standard input is duplicated from file descriptor .I digit (see .IR dup (2)). Similarly for the standard output using .BR >& .IR digit . .TP .B <&\- The standard input is closed. Similarly for the standard output using .BR >&\- . .PP If one of the above is preceded by a digit, then the file descriptor number referred to is that specified by the digit (instead of the default 0 or 1). For example: .RS .PP \&.\|.\|. \|2>&1 .RE .PP means file descriptor 2 is to be opened for writing as a duplicate of file descriptor 1. .PP The order in which redirections are specified is significant. The shell evaluates each redirection in terms of the .RI ( "file descriptor" ", " file ) association at the time of evaluation. For example: .RS .PP \&.\|.\|. \|1>\f2fname\^\fP 2>&1 .RE .PP first associates file descriptor 1 with file .IR fname\^ . It then associates file descriptor 2 with the file associated with file descriptor 1 (i.e. .IR fname\^ ). If the order of redirections were reversed, file descriptor 2 would be associated with the terminal (assuming file descriptor 1 had been) and then file descriptor 1 would be associated with file .IR fname\^ . .PP If a command is followed by .B & and job control is not active, then the default standard input for the command is the empty file .BR /dev/null . Otherwise, the environment for the execution of a command contains the file descriptors of the invoking shell as modified by input/output specifications. .SS Environment. The .I environment\^ (see .IR environ (7)) is a list of name-value pairs that is passed to an executed program in the same way as a normal argument list. The names must be .I identifiers\^ and the values are character strings. The shell interacts with the environment in several ways. On invocation, the shell scans the environment and creates a parameter for each name found, giving it the corresponding value and marking it .I export . Executed commands inherit the environment. If the user modifies the values of these parameters or creates new ones, using the .B export or .B typeset \-x commands they become part of the environment. The environment seen by any executed command is thus composed of any name-value pairs originally inherited by the shell, whose values may be modified by the current shell, plus any additions which must be noted in .B export or .B typeset \-x commands. .PP The environment for any .I simple-command\^ or function may be augmented by prefixing it with one or more parameter assignments. A parameter assignment argument is a word of the form .IR identifier=value . Thus: .RS .PP \s-1TERM\s+1=450 \|cmd \|args and .br (export \|\s-1TERM\s+1; \|\s-1TERM\s+1=450; \|cmd \|args) .RE .PP are equivalent (as far as the above execution of .I cmd\^ is concerned). .PP If the .B \-k flag is set, .I all\^ parameter assignment arguments are placed in the environment, even if they occur after the command name. The following first prints .B "a=b c" and then .BR c: .PP .RS .nf echo \|a=b \|c set \|\-k echo \|a=b \|c .fi .RE .SS Functions. .PP The .B function\^ keyword, described in the .I Commands section above, is used to define shell functions. Shell functions are read in and stored internally. Alias names are resolved when the function is read. Functions are executed like commands with the arguments passed as positional parameters. (See .I Execution below). .PP Functions execute in the same process as the caller and share all files, traps ( other than .SM .B EXIT and .SM .BR ERR ) and present working directory with the caller. A trap set on .SM .B EXIT inside a function is executed after the function completes. Ordinarily, variables are shared between the calling program and the function. However, the .B typeset special command used within a function defines local variables whose scope includes the current function and all functions it calls. .PP The special command .B return is used to return from function calls. Errors within functions return control to the caller. .PP Function identifiers can be listed with the .B \-f option of the .B typeset special command. The text of functions will also be listed. Function can be undefined with the .B \-f option of the .B unset special command. .PP Ordinarily, functions are unset when the shell executes a shell script. The .B \-xf option of the .B typeset command allows a function to be exported to scripts that are executed without a separate invocation of the shell. Functions that need to be defined across separate invocations of the shell should be placed in the .B .SM ENV file. .SS Jobs. .PP If the .B monitor option of the .B set command is turned on, an interactive shell associates a \fIjob\fR with each pipeline. It keeps a table of current jobs, printed by the .B jobs command, and assigns them small integer numbers. When a job is started asynchronously with .BR & , the shell prints a line which looks like: .PP .DT [1] 1234 .PP indicating that the job which was started asynchronously was job number 1 and had one (top-level) process, whose process id was 1234. .PP This paragraph and the next require features that are not in all versions of UNIX and may not apply. If you are running a job and wish to do something else you may hit the key \fB^Z\fR (control-Z) which sends a STOP signal to the current job. The shell will then normally indicate that the job has been `Stopped', and print another prompt. You can then manipulate the state of this job, putting it in the background with the .B bg command, or run some other commands and then eventually bring the job back into the foreground with the foreground command .BR fg . A \fB^Z\fR takes effect immediately and is like an interrupt in that pending output and unread input are discarded when it is typed. .PP A job being run in the background will stop if it tries to read from the terminal. Background jobs are normally allowed to produce output, but this can be disabled by giving the command ``stty tostop''. If you set this tty option, then background jobs will stop when they try to produce output like they do when they try to read input. .PP There are several ways to refer to jobs in the shell. The character .B % introduces a job name. If you wish to refer to job number 1, you can name it as .B %1 . Jobs can also be named by prefixes of the string typed in to .B kill or restart them. Thus, on systems that support job control, .RB ` fg .BR %ed ' would normally restart a suspended .IR ed (1) job, if there were a suspended job whose name began with the string `ed'. .PP The shell maintains a notion of the current and previous jobs. In output pertaining to jobs, the current job is marked with a .B + and the previous job with a .BR \- . The abbreviation .B %+ refers to the current job and .B %\- refers to the previous job. .B %% is also a synonym for the current job. .PP This shell learns immediately whenever a process changes state. It normally informs you whenever a job becomes blocked so that no further progress is possible, but only just before it prints a prompt. This is done so that it does not otherwise disturb your work. .PP When you try to leave the shell while jobs are running or stopped, you will be warned that `You have stopped(running) jobs.' You may use the .B jobs command to see what they are. If you do this or immediately try to exit again, the shell will not warn you a second time, and the stopped jobs will be terminated. .SS Signals. The \s-1INT\s+1 and \s-1QUIT\s+1 signals for an invoked command are ignored if the command is followed by .B & and job .B monitor option is not active. Otherwise, signals have the values inherited by the shell from its parent, with the exception of signal 11 (but see also the .B trap command below). .SS Execution. Each time a command is executed, the above substitutions are carried out. If the command name matches one of the .I "Special Commands\^" listed below, it is executed within the current shell process. Next, the command name is checked to see if it matches one of the user defined functions. If it does, the positional parameters are saved and then reset to the arguments of the .I function\^ call. When the .I function\^ completes or issues a .BR return , the positional parameter list is restored and any trap set on .SM .B EXIT within the function is executed. The value of a .I function\^ is the value of the last command executed. A function is also executed in the current shell process. If a command name is not a .I "special command\^" or a user defined .IR function , a process is created and an attempt is made to execute the command via .IR exec (2). .PP The shell parameter .B .SM PATH defines the search path for the directory containing the command. Alternative directory names are separated by a colon .RB ( : ). The default path is .B :/bin:/usr/bin (specifying the current directory, .BR /bin , and .BR /usr/bin , in that order). Note that the current directory is specified by a null path name, which can appear immediately after the equal sign, between colon delimiters, or at the end of the path list. If the command name contains a \f3/\fP then the search path is not used. Otherwise, each directory in the path is searched for an executable file. If the file has execute permission but is not a directory or an .B a.out file, it is assumed to be a file containing shell commands. A sub-shell is spawned to read it. All non-exported aliases, functions, and named parameters are removed in this case. A parenthesized command is also executed in a sub-shell. .SS Command Re-entry. The text of the last .B .SM HISTSIZE (default 128) commands entered from a terminal device is saved in a .I history file. The file .B \s-1$HOME\s+1/.history is used if the .B .SM HISTFILE variable is not set or is not writable. A shell can access the commands of all .I interactive shells which use the same named .SM .BR HISTFILE . The special command .B fc\^ is used to list or edit a portion this file. The portion of the file to be edited or listed can be selected by number or by giving the first character or characters of the command. A single command or range of commands can be specified. If you do not specify an editor program as an argument to .B fc\^ then the value of the parameter .SM .B FCEDIT is used. If .SM .B FCEDIT is not defined then .I /bin/ed is used. The edited command(s) is printed and re-executed upon leaving the editor. The editor name .B \- is used to skip the editing phase and to re-execute the command. In this case a substitution parameter of the form \f2old\fP\f3=\fP\f2new\fP can be used to modify the command before execution. For example, if .B r is aliased to .B \(fmfc \-e \-\(fm then typing `\f3r bad=good c\fP' will re-execute the most recent command which starts with the letter .BR c , replacing the string .B bad with the string .BR good . .SS In-line Editing Options Normally, each command line entered from a terminal device is simply typed followed by a new-line (`RETURN' or `LINE\ FEED'). If either the .IR emacs , .IR gmacs , or .I vi option is active, the user can edit the command line. To be in either of these edit modes .B set the corresponding option. An editing option is automatically selected each time the .SM .B VISUAL or .SM .B EDITOR variable is assigned a value ending in either of these option names. .PP The editing features require that the user's terminal accept `RETURN' as carriage return without line feed and that a space (`\ ' must overwrite the current character on the screen. ADM terminal users should set the "space\ -\ advance" switch to `space'. Hewlett-Packard series 2621 terminal users should set the straps to `bcGHxZ\ etX'. .PP The editing modes implement a concept where the user is looking through a window at the current line. The window width is the value of .SM .B COLUMNS if it is defined, otherwise 80. If the line is longer than the window width minus two, a mark is displayed at the end of the window to notify the user. As the cursor moves and reaches the window boundaries the window will be centered about the cursor. The mark is a .BR > " (" .BR < ", " .BR * ) if the line extends on the right (left, both) side(s) of the window. .SS Emacs Editing Mode This mode is entered by enabling either the .I emacs or .I gmacs option. The only difference between these two modes is the way they handle .BR ^T . To edit, the user moves the cursor to the point needing correction and then inserts or deletes characters or words as needed. All the editing commands are control characters or escape sequences. The notation for control characters is caret ( .B ^ ) followed by the character. For example, .B ^F is the notation for control .BR F . This is entered by depressing `f' while holding down the `CTRL' (control) key. The `SHIFT' key is .I not depressed. (The notation .B ^? indicates the DEL (delete) key.) .PP The notation for escape sequences is .B M- followed by a character. For example, .B M-f (pronounced Meta f) is entered by depressing ESC (ascii .B 033 ) followed by `f'. ( .B M-F would be the notation for ESC followed by `SHIFT' (capital) `F'.) .PP All edit commands operate from any place on the line (not just at the beginning). Neither the "RETURN" nor the "LINE FEED" key is entered after edit commands except when noted. .PP .PD 0 .TP 10 .BI ^F Move cursor forward (right) one character. .PP .TP 10 .BI M-f Move cursor forward one word. (The editor's idea of a word is a string of characters consisting of only letters, digits and underscores.) .PP .TP 10 .BI ^B Move cursor backward (left) one character. .PP .TP 10 .BI M-b Move cursor backward one word. .PP .TP 10 .BI ^A Move cursor to start of line. .PP .TP 10 .BI ^E Move cursor to end of line. .PP .TP 10 .BI ^] char Move cursor to character .I char on current line. .PP .TP 10 .BI ^X^X Interchange the cursor and mark. .PP .TP 10 .I erase (User defined erase character as defined by the stty command, usually .B ^H or .BR # .) Delete previous character. .PP .TP 10 .BI ^D Delete current character. .PP .TP 10 .BI M-d Delete current word. .PP .TP 10 .BI M-^H (Meta-backspace) Delete previous word. .PP .TP 10 .BI M-h Delete previous word. .PP .TP 10 .BI M-^? (Meta-DEL) Delete previous word (if your interrupt character is .B ^? (DEL, the default) then this command will not work). .PP .TP 10 .BI ^T Transpose current character with next character in .I emacs mode. Transpose two previous characters in .I gmacs mode. .PP .TP 10 .BI ^C Capitalize current character. .PP .TP 10 .BI M-C Capitalize current word. .PP .TP 10 .BI ^K Kill from the cursor to the end of the line. If given a parameter of zero then kill from the start of line to the cursor. .PP .TP 10 .BI ^W Kill from the cursor to the mark. .PP .TP 10 .BI M-p Push the region from the cursor to the mark on the stack. .PP .TP 10 .I kill (User defined kill character as defined by the stty command, usually .B ^G or .BR @ .) Kill the entire current line. If two .I kill characters are entered in succession, all kill characters from then on cause a line feed (useful when using paper terminals). .PP .TP 10 .BI ^Y Restore last item removed from line. (Yank item back to the line.) .PP .TP 10 .BI ^L Line feed and print current line. .PP .TP 10 .BI ^@ (Null character) Set mark. .PP .TP 10 .BI M- (Meta space) Set mark. .PP .TP 10 .BI ^J (New\ line) Execute the current line. .PP .TP 10 .BI ^M (Return) Execute the current line. .PP .TP 10 .I eof End-of-file character, normally .BR ^D , will terminate the shell if the current line is null. .PP .TP 10 .BI ^P Fetch previous command. Each time .B ^P is entered the previous command back in time is accessed. .PP .TP 10 .BI M-< Fetch the least recent (oldest) history line. .PP .TP 10 .BI M-> Fetch the most recent (youngest) history line. .PP .TP 10 .BI ^N Fetch next command. Each time .B ^N is entered the next command forward in time is accessed. .PP .TP 10 .BI ^R string Reverse search history for a previous command line containing .IR string . If a parameter of zero is given the search is forward. .I String is terminated by a "RETURN" or "NEW\ LINE". .PP .TP 10 .B ^O Operate \- Execute the current line and fetch the next line relative to current line from the history file. .PP .TP 10 .BI M- digits (Escape) Define numeric parameter, the digits are taken as a parameter to the next command. The commands that accept a parameter are .BR ^F , .BR ^B , .IR erase , .BR ^D , .BR ^K , .BR ^R , .B ^P and .BR ^N . .PP .TP 10 .BI M- letter Soft-key \- Your alias list is searched for an alias by the name .BI _ letter and if an alias of this name is defined, its value will be inserted on the line. The .I letter must not be one of the above meta-functions. .PP .TP 10 .B M-_ The last parameter of the previous command is inserted on the line. .PP .TP 10 .B M-. The last parameter of the previous command is inserted on the line. .PP .TP 10 .B M-* Attempt file name generation on the current word. .PP .TP 10 .BI ^U Multiply parameter of next command by 4. .PP .TP 10 .BI \e Escape next character. Editing characters, the user's erase, kill and interrupt (normally .B ^? ) characters may be entered in a command line or in a search string if preceded by a .BR \e . The .B \e removes the next character's editing features (if any). .PP .TP 10 .BI ^V Display version of the shell. .PD .SS Vi Editing Mode There are two typing modes. Initially, when you enter a command you are in the .I input\^ mode. To edit, the user enters .I control\^ mode by typing ESC ( .B 033 ) and moves the cursor to the point needing correction and then inserts or deletes characters or words as needed. Most control commands accept an optional repeat .I count prior to the command. .P When in vi mode on most systems, canonical processing is initially enabled and the command will be echoed again if the speed is 1200 baud or greater and it contains any control characters or less than one second has elapsed since the prompt was printed. The ESC character terminates canonical processing for the remainder of the command and the user can than modify the command line. This scheme has the advantages of canonical processing with the type-ahead echoing of raw mode. .P If the option .B viraw\^ is also set, the terminal will always have canonical processing disabled. This mode is implicit for systems that do not support two alternate end of line delimiters, and may be helpful for certain terminals. .SS "\ \ \ \ \ Input Edit Commands" .PP .RS By default the editor is in input mode. .PD 0 .TP 10 .I erase (User defined erase character as defined by the stty command, usually .B ^H or .BR # .) Delete previous character. .TP 10 .BI ^W Delete the previous blank separated word. .TP 10 .BI ^D Terminate the shell. .TP 10 .BI ^V Escape next character. Editing characters, the user's erase or kill characters may be entered in a command line or in a search string if preceded by a .BR ^V . The .B ^V removes the next character's editing features (if any). .TP 10 .BI \e Escape the next .I erase or .I kill character. .P .RE .SS "\ \ \ \ \ Motion Edit Commands" .RS These commands will move the cursor. .TP 10 [\f2count\fP]\f3l\fP Cursor forward (right) one character. .TP 10 [\f2count\fP]\f3w\fP Cursor forward one alpha-numeric word. .TP 10 [\f2count\fP]\f3W\fP Cursor to the beginning of the next word that follows a blank. .TP 10 [\f2count\fP]\f3e\fP Cursor to end of word. .TP 10 [\f2count\fP]\f3E\fP Cursor to end of the current blank delimited word. .TP 10 [\f2count\fP]\f3h\fP Cursor backward (left) one character. .TP 10 [\f2count\fP]\f3b\fP Cursor backward one word. .TP 10 [\f2count\fP]\f3B\fP Cursor to preceding blank separated word. .TP 10 [\f2count\fP]\f3f\fP\f2c\fP Find the next character \fIc\fP in the current line. .TP 10 [\f2count\fP]\f3F\fP\f2c\fP Find the previous character \fIc\fP in the current line. .TP 10 [\f2count\fP]\f3t\fP\f2c\fP Equivalent to .B f followed by .BR h . .TP 10 [\f2count\fP]\f3T\fP\f2c\fP Equivalent to .B F followed by .BR l . .TP 10 .B ; Repeats the last single character find command, .BR f , .BR F , .BR t , or .BR T . .TP 10 .B , Reverses the last single character find command. .TP 10 .B 0 Cursor to start of line. .TP 10 .B ^ Cursor to first non-blank character in line. .TP 10 .B $ Cursor to end of line. .RE .SS "\ \ \ \ \ Search Edit Commands" .RS These commands access your command history. .TP 10 [\f2count\fP]\f3k\fP Fetch previous command. Each time .B k is entered the previous command back in time is accessed. .TP 10 [\f2count\fP]\f3\-\fP Equivalent to .BR k . .TP 10 [\f2count\fP]\f3j\fP Fetch next command. Each time .B j is entered the next command forward in time is accessed. .TP 10 [\f2count\fP]\f3+\fP Equivalent to .BR j . .TP 10 [\f2count\fP]\f3G\fP The command number .I count is fetched. The default is the least recent history command. .TP 10 .BI / string Search backward through history for a previous command containing .IR string . .I String is terminated by a "RETURN" or "NEW\ LINE". If \fIstring\fP is null the previous string will be used. .TP 10 .BI ? string Same as .B / except that search will be in the forward direction. .TP 10 .B n Search for next match of the last pattern to .B / or .B ? commands. .TP 10 .B N Search for next match of the last pattern to .B / or .BR ? , but in reverse direction. Search history for the \fIstring\fP entered by the previous \fB/\fP command. .RE .SS "\ \ \ \ \ Text Modification Edit Commands" .RS These commands will modify the line. .TP 10 .B a Enter input mode and enter text after the current character. .TP 10 .B A Append text to the end of the line. Equivalent to .BR $a . .TP 10 [\f2count\fP]\f3c\fP\f2motion\fP .TP 10 \f3c\fP[\f2count\fP]\f2motion\fP Delete current character through the character .I motion moves the cursor to and enter input mode. If \fImotion\fP is .BR c , the entire line will be deleted and input mode entered. .TP 10 .B C Delete the current character through the end of line and enter input mode. Equivalent to .BR c$ . .TP 10 .B S Equivalent to .BR cc . .TP 10 .B D Delete the current character through the end of line. .TP 10 [\f2count\fP]\f3d\fP\f2motion\fP .TP 10 \f3d\fP[\f2count\fP]\f2motion\fP Delete current character through the character .I motion moves the cursor to. Equivalent to .BR d$ . If \fImotion\fP is .B d , the entire line will be deleted. .TP 10 .B i Enter input mode and insert text before the current character. .TP 10 .B I Insert text before the beginning of the line. Equivalent to the two character sequence .BR ^i . .TP 10 [\f2count\fP]\f3P\fP Place the previous text modification before the cursor. .TP 10 [\f2count\fP]\f3p\fP Place the previous text modification after the cursor. .TP 10 .B R Enter input mode and replace characters on the screen with characters you type overlay fashion. .TP 10 .BI r c Replace the current character with .IR c . .TP 10 [\f2count\fP]\f3x\fP Delete current character. .TP 10 [\f2count\fP]\f3X\fP Delete preceding character. .TP 10 [\f2count\fP]\f3.\fP Repeat the previous text modification command. .TP 10 .B \(ap Invert the case of the current character and advance the cursor. .TP 10 [\f2count\fP]\f3_\fP Causes the .I count\^ word of the previous command to be appended and input mode entered. The last word is used if .I count\^ is omitted. .TP 10 .B * Causes an .B * to be appended to the current word and file name generation attempted. If no match is found, it rings the bell. Otherwise, the word is replaced by the matching pattern and input mode is entered. .RE .SS "\ \ \ \ \ Other Edit Commands" .RS Miscellaneous commands. .TP 10 .B u Undo the last text modifying command. .TP 10 .B U Undo all the text modifying commands performed on the line. .TP 10 [\f2count\fP]\f3v\fP Returns the command .BI "fc \-e ${\s-1VISUAL\s+1:\-${\s-1EDITOR\s+1:\-vi}}" " count" in the input buffer. If .I count\^ is omitted, then the current line is used. .TP 10 .BI ^L Line feed and print current line. Has effect only in control mode. .TP 10 .BI ^J (New\ line) Execute the current line, regardless of mode. .TP 10 .BI ^M (Return) Execute the current line, regardless of mode. .TP 10 .B \# Equivalent to \f3I#\fP\f2\fP. Useful for causing the current line to be inserted in the history without being executed. .RE .PD .SS Special Commands. The following simple-commands are executed in the shell process. Input/Output redirection is permitted. File descriptor 1 is the default output location. Parameter assignment lists preceding the command do not remain in effect when the command completes unless noted. .TP \f3:\fP \*(OK \f2arg\^\fP .\|.\|. \*(CK Parameter assignments remain in effect after the command completes. The command only expands parameters. A zero exit code is returned. .br .ne 2 .TP \f3\|. \f2file\^\fP \*(OK \f2arg\^\fP .\|.\|. \*(CK Parameter assignments remain in effect after the command completes. Read and execute commands from .I file\^ and return. The commands are executed in the current Shell environment. The search path specified by .B .SM PATH is used to find the directory containing .IR file . If any arguments .I arg\^ are given, they become the positional parameters. Otherwise the positional parameters are unchanged. .TP \f3alias\fP \*(OK \f3\-tx\fP \*(CK \*(OK \f2name\fP\*(OK \f2=value\^\fP \*(CK .\|.\|. \*(CK .I Alias\^ with no arguments prints the list of aliases in the form .I name=value\^ on standard output. An .I alias\^ is defined for each name whose .I value\^ is given. A trailing space in .I value\^ causes the next word to be checked for alias substitution. The .B \-t flag is used to set and list tracked aliases. The value of a tracked alias is the full pathname corresponding to the given .IR name . The value becomes undefined when the value of .SM .B PATH is reset but the aliases remained tracked. Without the .B \-t flag, for each .I name\^ in the argument list for which no .I value\^ is given, the name and value of the alias is printed. The .B \-x flag is used to set or print exported aliases. An exported alias is defined across sub-shell environments. Alias returns true unless a .I name\^ is given for which no alias has been defined. .TP \f3bg\fP \*(OK \f3%\f2job\^\fP \*(CK This command is only built-in on systems that support job control. Puts the specified .I job\^ into the background. The current job is put in the background if .I job\^ is not specified. .TP \f3break\fP \*(OK \f2n\^\fP \*(CK Exit from the enclosing .BR for .BR while .BR until or .B select\^ loop, if any. If .I n\^ is specified then break .I n\^ levels. .TP \f3continue\fP \*(OK \f2n\^\fP \*(CK Resume the next iteration of the enclosing .BR for .BR while .BR until or .B select\^ loop. If .I n\^ is specified then resume at the .IR n -th enclosing loop. .TP .PD 0 \f3cd\fP \*(OK \f2arg\^\fP \*(CK .TP \f3cd\fP \f2old\^\fP \f2new\^\fP .PD This command can be in either of two forms. In the first form it changes the current directory to .IR arg . If .I arg\^ is .B \- the directory is changed to the previous directory. The shell parameter .B .SM HOME is the default .IR arg . The parameter .SM .B PWD is set to the current directory. The shell parameter .B .SM CDPATH defines the search path for the directory containing .IR arg . Alternative directory names are separated by a colon .RB ( : ). The default path is .B (specifying the current directory). Note that the current directory is specified by a null path name, which can appear immediately after the equal sign or between the colon delimiters anywhere else in the path list. If .I arg begins with a \f3/\fP then the search path is not used. Otherwise, each directory in the path is searched for .IR arg . .P The second form of .B cd substitutes the string .I new for the string .I old in the current directory name, .SM .B PWD and tries to change to this new directory. .P The .B cd\^ command may not be executed by .I rsh\^. .TP \f3eval\fP \*(OK \f2arg\^\fP .\|.\|. \*(CK The arguments are read as input to the shell and the resulting command(s) executed. .TP \f3exec\fP \*(OK \f2arg\^\fP .\|.\|. \*(CK Parameter assignments remain in effect after the command completes. If .I arg\^ is given, the command specified by the arguments is executed in place of this shell without creating a new process. Input/output arguments may appear and affect the current process. If no arguments are given the effect of this command is to modify file descriptors as prescribed by the input/output redirection list. In this case, any file descriptor numbers greater than 2 that are opened with this mechanism are closed when invoking another program. .TP \f3exit\fP \*(OK \f2n\^\fP \*(CK Causes the shell to exit with the exit status specified by .IR n . If .I n\^ is omitted then the exit status is that of the last command executed. An end-of-file will also cause the shell to exit except for a shell which has the .I ignoreeof option (See .B set below) turned on. .TP \f3export\fP \*(OK \f2name\^\fP .\|.\|. \*(CK The given .IR name s are marked for automatic export to the .I environment\^ of subsequently-executed commands. .TP .PD 0 \f3fc\fP \*(OK \f3\-e \f2ename\^\fP \ \*(CK \*(OK \f3\-\f3nlr\^\f1 \*(CK \*(OK \f2first\^\fP \*(CK \*(OK \f2last\^\fP \*(CK .TP \f3fc \-e \-\fP \*(OK \f2old\fP\f3\=\fP\f2new\^\fP \*(CK \*(OK \f2command\^\fP \*(CK .PD In the first form, a range of commands from .I first\^ to .I last\^ is selected from the last .SM .B HISTSIZE commands that were typed at the terminal. The arguments .I first\^ and .I last\^ may be specified as a number or as a string. A string is used to locate the most recent command starting with the given string. A negative number is used as an offset to the current command number. If the flag .BR \-l , is selected, the commands are listed on standard output. Otherwise, the editor program .I ename\^ is invoked on a file containing these keyboard commands. If .I ename\^ is not supplied, then the value of the parameter .SM .B FCEDIT (default /bin/ed) is used as the editor. When editing is complete, the edited command(s) is executed. .I last\^ is not specified then it will be set to .IR first . If .I first\^ is not specified the default is the previous command for editing and \-16 for listing. The flag .B \-r reverses the order of the commands and the flag .B \-n suppresses command numbers when listing. In the second form the .I command\^ is re-executed after the substitution \f2old\^\fP\f3=\fP\f2new\^\fP is performed. .TP \f3fg\fP \*(OK \f3%\f2job\^\fP \*(CK This command is only built-in on systems that support job control. If .I job\^ is specified it brings it to the foreground. Otherwise, the current job is brought into the foreground. .TP \f3jobs\fP \*(OK \f3\-l\^\fP \*(CK Lists the active jobs; given the .B \-l options lists process id's in addition to the normal information. .TP \f3kill\fP \*(OK \f3\-\f2sig\^\fP \*(CK \f2process\^\fP .\|.\|. Sends either the TERM (terminate) signal or the specified signal to the specified jobs or processes. Signals are either given by number or by names (as given in .I /usr/include/signal.h, stripped of the prefix ``SIG''). The signal names are listed by .BR "kill \-l'" . There is no default, saying just `kill' does not send a signal to the current job. If the signal being sent is TERM (terminate) or HUP (hangup), then the job or process will be sent a CONT (continue) signal if it is stopped. The argument .I process\^ can be either a process id or a job. .TP \f3let\fP \f2arg\^\fP .\|.\|. Each .I arg is an .IR "arithmetic expression" to be evaluated. All calculations are done as long integers and no check for overflow is performed. Expressions consist of constants, named parameters, and operators. The following set of operators, listed in order of decreasing precedence, have been implemented: .RS .PD 0 .TP .B \- unary minus .TP .B ! logical negation .TP .B "* / %" .br multiplication, division, remainder .TP .B "+ \-" addition, subtraction .TP .B "<= >= < >" .br comparison .TP .B "== !=" .br equality inequality .TP .B = arithmetic replacement .PD .PP Sub-expressions in parentheses .B (\|) are evaluated first and can be used to override the above precedence rules. The evaluation within a precedence group is from right to left for the .B = operator and from left to right for the others. .PP A parameter name must be a valid .IR identifier . When a parameter is encountered, the value associated with the parameter name is substituted and expression evaluation resumes. Up to nine levels of recursion are permitted. .PP The return code is 0 if the value of the last expression is non-zero, and 1 otherwise. .RE .TP \f3newgrp\fP \*(OK \f2arg\^\fP .\|.\|. \*(CK Equivalent to .BI "exec newgrp" " arg\^" \&.\|.\|.\^. .TP \f3print\fP \*(OK \f3\-Rnprsu\^\fP\*(OK\f2n\fP \*(CK \*(CK \*(OK \f2arg\^\fP .\|.\|. \*(CK The shell output mechanism. With no flags or with flag .BR \- , the arguments are printed on standard output as described by .IR echo (1). In raw mode, .B \-R or .BR \-r , the escape conventions of .I echo are ignored. The .B \-R option will print all subsequent arguments and options other than .BR \-n . The .B \-p option causes the arguments to be written onto the pipe of the process spawned with .B \(bv& instead of standard output. The .B \-s option causes the arguments to be written onto the history file instead of standard output. The .B \-u flag can be used to specify a one digit file descriptor unit number .B n\^ on which the output will be placed. The default is 1. If the flag .B \-n is used, no .B new-line\^ is added to the output. .TP \f3read\fP \*(OK \f3\-prsu\^\fP\*(OK \f2n\^\fP \*(CK \*(CK \*(OK \f2name\f3?\f2prompt\^\f1 \*(CK \*(OK \f2name\^\fP .\|.\|. \*(CK The shell input mechanism. One line is read and is broken up into words using the characters in .B .SM IFS as separators. In raw mode, .B \-r, a .B \e at the end of a line does not signify line continuation. The first word is assigned to the first .IR name , the second word to the second .IR name , etc., with leftover words assigned to the last .IR name . The .B \-p option causes the input line to be taken from the input pipe of a process spawned by the shell using .BR \(bv& . If the .B \-s fag is present, the input will be saved as a command in the history file. The flag .B \-u can be used to specify a one digit file descriptor unit to read from. The file descriptor can be opened with the .B exec\^ special command. The default value of .I n\^ is 0. If .IR name is omitted then .SM .B REPLY is used as the default .IR name. The return code is 0 unless an end-of-file is encountered. An end-of-file with the .B \-p option causes cleanup for this process so that another can be spawned. If the first argument contains a .BR ? , the remainder of this word is used as a .I prompt\^ when the shell is interactive. If the given file descriptor is open for writing and is a terminal device then the prompt is placed on this unit. Otherwise the prompt is issued on file descriptor 2. The return code is 0 unless an end-of-file is encountered. .TP \f3readonly\fP \*(OK \f2name\fP .\|.\|. \*(CK The given .IR names are marked readonly and these names cannot be changed by subsequent assignment. .TP \f3return\fP \*(OK \f2n\^\fP \*(CK Causes a shell .I function to return to the invoking script with the return status specified by .IR n . If .I n\^ is omitted then the return status is that of the last command executed. If .B return is invoked while not in a .I function then it is the same as an .BR exit . .TP \f3set\fP \*(OK \f3\-aefhkmnostuvx\fP \*(CK \*(OK \f3\-o\fP \f2option\^\fP .\|.\|. \*(CK \*(OK \f2arg\^\fP .\|.\|. \*(CK The flags for this command have meaning as follows: .RS .PD 0 .TP 8 .B \-a All subsequent parameters that are defined are automatically exported. .TP 8 .B \-e If the shell is non-interactive and if a command fails, execute the .SM .B ERR trap, if set, and exit immediately. This mode is disabled while reading profiles. .TP 8 .B \-f Disables file name generation. .TP 8 .B \-h Each command whose name is an .I identifier\^ becomes a tracked alias when first encountered. .TP 8 .B \-k All parameter assignment arguments are placed in the environment for a command, not just those that precede the command name. .TP 8 .B \-m Background jobs will run in a separate process group and a line will print upon completion. The exit status of background jobs is reported in a completion message. On systems with job control, this flag is turned on automatically for interactive shells. .TP 8 .B \-n Read commands but do not execute them. .TP 8 .B \-o The following argument can be one of the following option names: .RS .TP 8 .B allexport Same as .BR \-a . .TP 8 .B errexit Same as .BR \-e . .TP 8 .B emacs Puts you in an .I emacs style in-line editor for command entry. .TP 8 .B gmacs Puts you in a .I gmacs style in-line editor for command entry. .TP 8 .B ignoreeof The shell will not exit on end-of-file. The command .B exit must be used. .TP 8 .B keyword Same as .BR \-k . .TP 8 .B markdirs All directory names resulting from file name generation have a trailing .B / appended. .TP 8 .B monitor Same as .BR \-m . .TP 8 .B noexec Same as .BR \-n . .TP 8 .B noglob Same as .BR \-f . .TP 8 .B nounset Same as .BR \-u . .TP 8 .B verbose Same as .BR \-v . .TP 8 .B trackall Same as .BR \-h . .TP 8 .B vi Puts you in insert mode of a .I vi\^ style in-line editor until you hit escape character .BR 033 . This puts you in move mode. A return sends the line. .TP 8 .B viraw Each character is processed as it is typed in .I vi\^ mode. .TP 8 .B xtrace Same as .BR \-x . .TP 8 If no option name is supplied then the current option settings are printed. .RE .TP 8 .B \-s Sort the positional parameters. .TP 8 .B \-t Exit after reading and executing one command. .TP 8 .B \-u Treat unset parameters as an error when substituting. .TP 8 .B \-v Print shell input lines as they are read. .TP 8 .B \-x Print commands and their arguments as they are executed. .TP 8 .B \- Turns off .B \-x and .B \-v flags and stops examining arguments for flags. .TP 8 .B \-\- Do not change any of the flags; useful in setting .B $1 to a value beginning with .BR \- . If no arguments follow this flag then the positional parameters are unset. .PD .PP Using .B \+ rather than .B \- causes these flags to be turned off. These flags can also be used upon invocation of the shell. The current set of flags may be found in .BR $\- . The remaining arguments are positional parameters and are assigned, in order, .if t to\p .if n to .BR $1 , .BR $2 , \&.\|.\|.\^. If no arguments are given then the values of all names are printed on the standard output. .RE .TP \f3shift\fP \*(OK \f2n\^\fP \*(CK .br The positional parameters from \f3$\fP\f2n\fP\f3+1\fP \&.\|.\|. are renamed .B $1 \&.\|.\|.\^ , default .I n\^ is 1. The parameter .I n\^ can be any arithmetic expression that evaluates to a non-negative number less than or equal to .BR $# . .TP \f3test\fP \*(OK \f2expr\^\fP \*(CK .br Evaluate conditional expression .IR expr . See .IR test (1) for usage and description. The arithmetic comparison operators are not restricted to integers. They allow any arithmetic expression. Four additional primitive expressions are allowed: .RS .PD 0 .TP \f3\-L\fP \f2file\^\fP True if .I file\^ is a symbolic link. .TP \f2file1\^\fP \f3\-nt\fP \f2file2\^\fP True if .I file1\^ is newer than .IR file2 . .TP \f2file1\^\fP \f3\-ot\fP \f2file2\^\fP True if .I file1\^ is older than .IR file2 . .TP \f2file1\^\fP \f3\-ef\fP \f2file2\^\fP True if .I file1\^ has the same device and i-node number as .IR file2 . .PD .RE .TP \f3times\fP .br Print the accumulated user and system times for the shell and for processes run from the shell. .TP \f3trap\fP \*(OK \f2arg\^\fP \*(CK \*(OK \f2sig\^\fP \*(CK .\|.\|. .I arg\^ is a command to be read and executed when the shell receives signal(s) .IR sig . (Note that .I arg\^ is scanned once when the trap is set and once when the trap is taken.) Each .I sig\^ can be given as a number or as the name of the signal. Trap commands are executed in order of signal number. Any attempt to set a trap on a signal that was ignored on entry to the current shell is ineffective. An attempt to trap on signal 11 (memory fault) produces an error. If .I arg\^ is omitted or is .BR \- , then all trap(s) .I sig\^ are reset to their original values. If .I arg\^ is the null string then this signal is ignored by the shell and by the commands it invokes. If .I sig\^ is .SM .B ERR then .I arg\^ will be executed whenever a command has a non-zero exit code. This trap is not inherited by functions. If .I sig\^ is .B 0 or .SM .B EXIT and the .B trap statement is executed inside the body of a function, then the command .I arg\^ is executed after the function completes. If .I sig\^ is .B 0 or .SM .B EXIT for a .B trap set outside any function then the command .I arg\^ is executed on exit from the shell. The .B trap command with no arguments prints a list of commands associated with each signal number. .TP \f3typeset\fP \*(OK \f3\-FLRZefilprtux\^\fP\*(OK\f2n\fP \*(CK \*(OK \f2name\fP\*(OK \f2=value\^\fP \*(CK \^ \*(CK .\|.\|. \*(CK Parameter assignments remain in effect after the command completes. When invoked inside a function, a new instance of the parameter .I name\^ is created. The parameter value and type are restored when the function completes. The following list of attributes may be specified: .RS .PD 0 .TP .B \-F This flag provides UNIX to host-name file mapping on non-UNIX machines. .TP .B \-L Left justify and remove leading blanks from .IR value . If .I n is non-zero it defines the width of the field, otherwise it is determined by the width of the value of first assignment. When the parameter is assigned to, it is filled on the right with blanks or truncated, if necessary, to fit into the field. Leading zeros are removed if the .B \-Z flag is also set. The .B \-R flag is turned off. .TP .B \-R Right justify and fill with leading blanks. If .I n is non-zero it defines the width of the field, otherwise it is determined by the width of the value of first assignment. The field is left filled with blanks or truncated from the end if the parameter is reassigned. The .B L flag is turned off. .TP .B \-Z Right justify and fill with leading zeros if the first non-blank character is a digit and the .B \-L flag has not been set. If .I n is non-zero it defines the width of the field, otherwise it is determined by the width of the value of first assignment. .TP .B \-e Tag the parameter as having an error. This tag is currently unused by the shell and can be set or cleared by the user. .TP .B \-f The names refer to function names rather than parameter names. No assignments can be made and the only other valid flag is .BR \-x . .TP .B \-i Parameter is an integer. This makes arithmetic faster. If .I n is non-zero it defines the output arithmetic base, otherwise the first assignment determines the output base. .TP .B \-l All upper-case characters converted to lower-case. The upper-case flag, .B \-u is turned off. .TP .B \-p The output of this command, if any, is written onto the two-way pipe .TP .B \-r The given .IR names are marked readonly and these names cannot be changed by subsequent assignment. .TP .B \-t Tags the named parameters. Tags are user definable and have no special meaning to the shell. .TP .B \-u All lower-case characters are converted to upper-case characters. The lower-case flag, .B \-l is turned off. .TP .B \-x The given .IR name s are marked for automatic export to the .I environment\^ of subsequently-executed commands. .PD .PP Using .B \+ rather than .B \- causes these flags to be turned off. If no .I name\^ arguments are given but flags are specified, a list of .I names\^ (and optionally the .I values\^ ) of the .I parameters\^ which have these flags set is printed. (Using .B \+ rather than .B \- keeps the values to be printed.) If no .IR name s and flags are given, the .I names\^ and .I attributes\^ of all .I parameters\^ are printed. .RE .TP \f3ulimit\fP \*(OK \f3\-cdfmpt\fP \*(CK \*(OK \f2n\^\fP \*(CK .RS .PD 0 .TP .B \-c imposes a size limit of .I n\^ blocks on the size of core dumps (\s-1BSD\s+1 only). .TP .B \-d imposes a size limit of .I n\^ blocks on the size of the data area (\s-1BSD\s+1 only). .TP .B \-f imposes a size limit of .I n\^ blocks on files written by child processes (files of any size may be read). .TP .B \-m imposes a soft limit of .I n\^ blocks on the size of physical memory (\s-1BSD\s+1 only). .TP .B \-p changes the pipe size to .I n\^ (\s-1UNIX\s+1/\s-1RT\s+1 only). .TP .B \-t imposes a time limit of .I n\^ seconds to be used by each process (\s-1BSD\s+1 only). .PD .PP If no option is given, .B \-f is assumed. If .I n\^ is not given the current limit is printed. .RE .TP \f3umask\fP \*(OK \f2nnn\^\fP \*(CK The user file-creation mask is set to .I nnn\^ (see .IR umask (2)). If .I nnn\^ is omitted, the current value of the mask is printed. .TP \f3unalias\fP \f2name\^\fP .\|.\|. The .IR parameters given by the list of .IR name s are removed from the .I alias\^ list. .TP \f3unset\fP \*(OK \f3\-f\fP \*(CK \f2name\^\fP .\|.\|. The parameters given by the list of .IR name s are unassigned, i. e., their values and attributes are erased. Readonly variables cannot be unset. If the flag, .BR \-f , is set, then the names refer to .I function\^ names. .TP \f3wait\fP \*(OK \f2n\^\fP \*(CK Wait for the specified process and report its termination status. If .I n\^ is not given then all currently active child processes are waited for. The return code from this command is that of the process waited for. .TP \f3whence\fP \*(OK \f3\-v\fP \*(CK \f2name\^\fP .\|.\|. For each .IR name , indicate how it would be interpreted if used as a command name. .P The flag, .BR \-v , produces a more verbose report. .SS Invocation. If the shell is invoked by .IR exec (2), and the first character of argument zero .RB ( $0 ) is .BR \- , then the shell is assumed to be a .I login shell and commands are read from .B /etc/profile and then from either .B .profile in the current directory or .BR \s-1$HOME\s+1/.profile , if either file exists. Next, commands are read from the file named by performing parameter substitution on the value of the environment parameter .SM .B ENV if the file exists. Commands are then read as described below; the following flags are interpreted by the shell when it is invoked: .PP .PD 0 .TP 10 .BI \-c "\| string\^" If the .B \-c flag is present then commands are read from .IR string . .TP .B \-s If the .B \-s flag is present or if no arguments remain then commands are read from the standard input. Shell output, except for the output of some of the .I Special commands\^ listed above, is written to file descriptor 2. .TP .B \-i If the .B \-i flag is present or if the shell input and output are attached to a terminal (as told by .IR gtty (2)) then this shell is .IR interactive . In this case \s-1TERMINATE\s+1 is ignored (so that \f3kill 0\fP does not kill an interactive shell) and \s-1INTERRUPT\s+1 is caught and ignored (so that .B wait is interruptible). In all cases, \s-1QUIT\s+1 is ignored by the shell. .TP .B \-r If the .B \-r flag is present the shell is a restricted shell. .PD .PP The remaining flags and arguments are described under the .B set command above. .SS Rsh Only. .I rsh is used to set up login names and execution environments whose capabilities are more controlled than those of the standard shell. The actions of .I rsh\^ are identical to those of .IR sh , except that the following are disallowed: .RS .PD 0 .PP changing directory (see .IR cd (1)), .br setting the value of .SM .B SHELL or .SM .BR PATH\*S, .br specifying path or command names containing .BR / , .br redirecting output .RB ( > and .BR >> ). .PD .RE .PP The restrictions above are enforced after \f3.profile\fP and the .SM .B ENV files are interpreted. .PP When a command to be executed is found to be a shell procedure, .I rsh\^ invokes .I sh\^ to execute it. Thus, it is possible to provide to the end-user shell procedures that have access to the full power of the standard shell, while imposing a limited menu of commands; this scheme assumes that the end-user does not have write and execute permissions in the same directory. .PP The net effect of these rules is that the writer of the .B .profile has complete control over user actions, by performing guaranteed setup actions and leaving the user in an appropriate directory (probably .I not\^ the login directory). .PP The system administrator often sets up a directory of commands (i.e., .BR /usr/rbin ) that can be safely invoked by .IR rsh . Some systems also provide a restricted editor .IR red . .SH EXIT STATUS Errors detected by the shell, such as syntax errors, cause the shell to return a non-zero exit status. If the shell is being used non-interactively then execution of the shell file is abandoned. Otherwise, the shell returns the exit status of the last command executed (see also the .B exit command above). .SH FILES /etc/passwd .br /etc/profile .br \s-1$HOME\s+1/\f3.\fPprofile .br /tmp/sh\(** .br /dev/null .SH SEE ALSO cat(1), cd(1), echo(1), emacs(1), env(1), gmacs(1), newgrp(1), test(1), umask(1), vi(1), dup(2), exec(2), fork(2), gtty(2), pipe(2), signal(2), umask(2), ulimit(2), wait(2), rand(3), a.out(5), profile(5), environ(7). .SH CAVEATS .PP If a command which is a .I "tracked alias" is executed, and then a command with the same name is installed in a directory in the search path before the directory where the original command was found, the shell will continue to .I exec\^ the original command. Use the .B \-t option of the .B alias\^ command to correct this situation .PP If you move the current directory or one above it, .B pwd\^ may not give the correct response. Use the .B cd\^ command with a full path name to correct this situation. .PP Some very old shell scripts contain a .B ^ as a synonym for the pipe character .BR \(bv .