NAME
sort - sort or merge files

SYNOPSIS
sort [ -mubdfinrtx ] [ +pos1 [ -pos2 ] ] ... [ -o name ]
[ -T directory ] [ name ] ...

DESCRIPTION
Sort sorts lines of all the named files together and writes the
result on the standard output. The name ‘-’ means the standard
input. If no input files are named, the standard input is sorted.

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.

b Ignore leading blanks (spaces and tabs) in field comparisons.
Note that the field must be specified, eg. sort -b +0.0 name.

d ‘Dictionary’ order: only letters, digits and blanks are
significant in comparisons.

f Fold upper case letters onto lower case.

i Ignore characters outside the ASCII range 040-0176 in
nonnumeric comparisons.

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. (Note that -0
is considered equal to 0.) Option n implies option b.

r Reverse the sense of comparisons.

tx ‘Tab character’ separating fields is x.

The notation +pos1 -pos2 restricts a sort key to a field beginning
at pos1 and ending just before pos2. Pos1 and pos2 each have the
form m.n, optionally followed by one or more of the flags bdfinr,
where m tells a number of fields to skip from the beginning of the
line and 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 option is in effect n is counted from the first
nonblank in the field; b is attached independently to pos2. A
missing .n means .0; a missing -pos2 means the end of the line.
Under the -tx option, fields are strings separated by x; otherwise
fields are nonempty nonblank strings separated by blanks.

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.

These option arguments are also understood:

c Check that the input file is sorted according to the ordering
rules; give no output unless the file is out of sort.

m Merge only, the input files are already sorted.

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.

T The next argument is the name of a directory in which
temporary files should be made.

u Suppress all but one in each set of equal lines. Ignored
bytes and bytes outside keys do not participate in this
comparison.

EXAMPLES
Print in alphabetical order all the unique spellings in a list of
words. Capitalized words differ from uncapitalized.

sort -u +0f +0 list

Print the password file (passwd(5)) sorted by user id number (the
3rd colon-separated field).

sort -t: +2n /etc/passwd

Print the first instance of each month in an already sorted file of
(month day) entries. The options -um with just one input file make
the choice of a unique representative from a set of equal lines
predictable.

sort -um +0 -1 dates

FILES
/usr/tmp/stm*, /tmp/* first and second tries for temporary files

SEE ALSO
uniq(1), comm(1), rev(1), join(1)

DIAGNOSTICS
Comments and exits with nonzero status for various trouble
conditions and for disorder discovered under option -c.

BUGS
Very long lines are silently truncated.