.TH SORT 1 
.SH NAME
sort \- sort and/or merge files
.SH SYNOPSIS
.B sort
[
.BR \-cmuMbdf\&inrt x
] [
.BR + pos1
[
.BR \- pos2
] ] .\|.\|. [
.B \-o
output\ ] [
.BR \-y memory
] [
.BR \-z recsize\ ]
[\ names\ ]
.SH DESCRIPTION
.I sort\^
sorts
lines of all the named files together
and writes the result on
the standard output.
The name
.B \-
means
the standard input.
If no input files are named, the standard input is sorted.
.PP
The default sort key is an entire line.
Default ordering is
lexicographic by bytes in machine
collating sequence.
The ordering is affected globally by the following options,
one or more of which may appear.
.TP 5
.B M
Compare as months.
The first three
non-blank characters
of the field
are folded
to lower case
and compared
so that `jan' < `feb' < .\|.\|. < `dec'.
Invalid fields
compare low to `jan'.
.TP 5
.B b
Ignore leading blanks (spaces and tabs) in field comparisons.
.TP
.B d
`Dictionary' order: only letters, digits and blanks
are significant in comparisons.
.TP
.B f
Fold upper case
letters onto lower case.
.TP
.B i
Ignore characters outside the
.SM ASCII
range 040-0176
in non-numeric comparisons.
.TP
.B n
An initial numeric string,
consisting of optional blanks, optional minus sign,
and zero or more digits with optional decimal point,
is sorted by arithmetic value.
Option
.B n
implies option
.BR b .
.TP
.B r
Reverse the sense of comparisons.
.TP
.BI t x\^
`Tab character' separating fields is
.IR x .
.PP
The notation
.BI + "pos1\| " \- pos2\^
restricts a sort key to a field beginning at
.I pos1\^
and ending just before
.IR pos2 .
.I pos1\^
and
.I pos2\^
each have the form
.IB m . n\^\f1,
optionally followed by one or more of the flags
.BR Mbdf\&inr ,
where
.I m\^
tells a number of fields to skip from the beginning of the line and
.I n\^
tells a number of characters to skip further.
If any flags are present they override all the global
ordering options for this key.
If the
.B b
option is in effect
.I n\^
is counted from the first non-blank in the field;
.B b
is attached independently to
.IR pos2 .
A missing
.BI \&. n\^
means
.BR \&. 0;
a missing
.BI \- pos2\^
means the end of the line.
Under the
.BI \-t x\^
option, fields are strings separated by
.IR x ;
otherwise fields are
non-empty non-blank strings separated by blanks.
The blanks separating fields
are considered
the first characters
in the field.
.PP
When there are multiple sort keys, later keys
are compared only after all earlier keys
compare equal.
Lines that otherwise compare equal are ordered
with all bytes significant.
.PP
These option arguments are also understood:
.TP 5
.B c
Check that the single input file is sorted according to the ordering rules;
give no output unless the file is out of sort.
.TP
.B m
Merge only, the input files are already sorted.
.TP
.B u
Suppress all but one in each
set of equal lines.
Ignored bytes
and bytes outside keys
do not participate in
this comparison.
.TP
.B o
The next argument is the name of an output file
to use instead of the standard output.
This file may be the same as one of the inputs.
.TP
.BI y memory
Suggests the use of the specified number of 
bytes of internal store in hopes of tuning performance;
0 is appropriate for very small files, a missing
number for huge ones.
.TP
.BI z recsize
provide for abnormally large records;
useful only with
.B \-c
and
.B \-m
.SH EXAMPLES
.TP
sort \-u +0f +0 list
Print in alphabetical order all the unique spellings
in a list of words
where capitalized words differ from uncapitalized.
.TP
sort \-t: +2n /etc/passwd
Print the password file
.RI ( passwd (5))
sorted by userid
(the third colon-separated field).
.TP
sort \-umM dates
Print the first instance of each month in an already sorted file.
Options
.B \-um
with just one input file make the choice of a
unique representative from a set of equal lines predictable.
.SH FILES
/usr/tmp/stm???
.SH SEE ALSO
comm(1),
join(1),
uniq(1).
.SH DIAGNOSTICS
Comments and exits with non-zero status for various trouble
conditions and for disorder discovered under option
.BR \-c .