term% cat index.txt SORT(1) General Commands Manual 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 lexico‐
graphic 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 pre‐
cedes etc. Invalid fields compare low to
-b Ignore leading white space (spaces and tabs) in field compar‐
isons.
-d `Phone directory' order: only letters, accented letters, digits
and white space are significant in comparisons.
-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-nu‐
meric 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 op‐
tional decimal point, is sorted by arithmetic 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.
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
independently 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 otherwise 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 participate in this com‐
parison.
-o The next argument is the name of an output file to use in‐
stead 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
Print in alphabetical order all the unique spellings
in a list of words where capitalized words differ from uncapi‐
talized.
Print the users file
sorted by user name (the second colon-separated field).
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 condi‐
tions and for disorder discovered under option -c.
BUGS
An external null character can be confused with an internally 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 provincial.
SORT(1)