SORT(1) SORT(1)
NAME
sort - sort and/or merge files
SYNOPSIS
sort [ -cmuMbdfinrwtx ] [ +pos1 [ -pos2 ] ... ] ... [ -k
pos1 [ ,pos2 ] ] ...
[ -o output ] [ -T dir ... ] [ option ... ] [ file
... ]
DESCRIPTION
Sort sorts lines of all the files together and writes the
result on the standard output. If no input files are named,
the standard input is sorted.
The default sort key is an entire line. Default ordering is
lexicographic by runes. The ordering is affected globally
by the following options, one or more of which may appear.
-M Compare as months. The first three non-white space
characters of the field are folded to upper case and
compared so that `JAN' precedes `FEB', etc. Invalid
fields compare low to `JAN'.
-b Ignore leading white space (spaces and tabs) in field
comparisons.
-d `Phone directory' order: only letters, accented let-
ters, digits and white space are significant in compar-
isons.
-f Fold lower case letters onto upper case. Accented
characters are folded to their non-accented upper case
form.
-i Ignore characters outside the ASCII range 040-0176 in
non-numeric comparisons.
-w Like -i, but ignore only tabs and spaces.
-n An initial numeric string, consisting of optional white
space, optional plus or minus sign, and zero or more
digits with optional decimal point, is sorted by arith-
metic value.
-g Numbers, like -n but with optional e-style exponents,
are sorted by value.
-r Reverse the sense of comparisons.
-tx `Tab character' separating fields is x.
Page 1 Plan 9 (printed 12/23/24)
SORT(1) SORT(1)
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 Mbdfginr, 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. 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 non-empty strings separated by white
space. White space before a field is part of the field,
except under option -b. A b flag may be attached indepen-
dently to pos1 and pos2.
The notation -k pos1[,pos2] is how POSIX sort defines
fields: pos1 and pos2 have the same format but different
meanings. The value of m is origin 1 instead of origin 0
and a missing .n in pos2 is the end of the field.
When there are multiple sort keys, later keys are compared
only after all earlier keys compare equal. Lines that oth-
erwise compare equal are ordered with all bytes significant.
These option arguments are also understood:
-c Check that the single input file is sorted
according to the ordering rules; give no output
unless the file is out of sort.
-m Merge; assume the input files are already sorted.
-u Suppress all but one in each set of equal lines.
Ignored bytes and bytes outside keys do not par-
ticipate in this comparison.
-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.
-Tdir Put temporary files in dir rather than in /tmp.
EXAMPLES
`sort -u +0f +0 list'
Print in alphabetical order all the unique spellings in
a list of words where capitalized words differ from
uncapitalized.
`sort -t: +1 /adm/users'
Print the users file sorted by user name (the second
colon-separated field).
`sort -umM dates'
Page 2 Plan 9 (printed 12/23/24)
SORT(1) SORT(1)
Print the first instance of each month in an already
sorted file. Options -um with just one input file make
the choice of a unique representative from a set of
equal lines predictable.
grep -n '^' input | sort -t: +1f +0n | sed 's/[0-9]*://'
A stable sort: input lines that compare equal will come
out in their original order.
FILES
/tmp/sort.<pid>.<ordinal>
SOURCE
/sys/src/cmd/sort.c
SEE ALSO
uniq(1), look(1)
DIAGNOSTICS
Sort comments and exits with non-null status for various
trouble conditions and for disorder discovered under option
-c.
BUGS
An external null character can be confused with an inter-
nally generated end-of-field character. The result can make
a sub-field not sort less than a longer field.
Some of the options, e.g. -i and -M, are hopelessly provin-
cial.
Page 3 Plan 9 (printed 12/23/24)