sort(1)

sort -- sort and/or merge files

Synopsis

sort [-m] [-o output] [-bdfiMnru] [-t x] [-T tmpdir] [-ykmem] [-zrecsz] [-k keydef] ... [file ... ]

sort -c [-bdfiMnru] [-t x] [-T tmpdir] [-ykmem] [-zrecsz] [-k keydef] ... [file]

Description

The sort command sorts lines of all the named files together and writes the result on the standard output. The standard input is read if - is used as a filename or no input files are named.

Comparisons are based on one or more sort keys extracted from each line of input. By default, there is one sort key, the entire input line, and ordering is lexicographic by bytes in machine collating sequence.

sort processes characters according to the locale specified in the LC_CTYPE, LC_COLLATE, and LC_NUMERIC environment variables (see LANG on environ(5)). Multibyte characters are not processed by some of the options.

The following options alter the default behavior:

-c

Check that the input file is sorted according to the ordering rules. If ``posix2'' is set, give no output and only vary the exit status.

-m

Merge only, the input files are already sorted.

-u

Unique: suppress all but one in each set of lines having equal keys.

-o output

The argument given 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 tmpdir

The sort command uses /var/tmp to store temporary files, unless you specify another directory using either the -T option or by setting the environment variable TMPDIR in the environment of the invoking process. Sorting large files, for example, may exhaust the available space in /var/tmp. In this case, you must specify an alternate temporary directory that has more free space, as shown in these examples:

TMPDIR=tmpdir export TMPDIR sort largefile sort -T tmpdir largefile

If the tmpdir you specify does not exist, sort will use

/tmp to store temporary files.

-ykmem

The amount of main memory used by sort has a large impact on its performance. Sorting a small file in a large amount of memory is a waste. If this option is omitted, sort begins using a system default memory size, and continues to use more space as needed. If this option is presented with a value (kmem), sort will start using that number of kilobytes of memory, unless the administrative minimum or maximum is violated, in which case the corresponding extremum will be used. Thus, -y0 is guaranteed to start with minimum memory. By convention, -y (with no argument) starts with maximum memory.

-zrecsz

The size of the longest line read is recorded in the sort phase so buffers can be allocated during the merge phase. If the sort phase is omitted via the -c or -m options, a popular system default size will be used. Lines longer than the buffer size will cause sort to terminate abnormally. Supplying the actual number of bytes in the longest line to be merged (or some larger value) will prevent abnormal termination.

If the sort phase is not omitted, then the maximum line size is calculated and used as the recsz, overriding the value of -z. Thus, the -z option is significant only when used with -c or -m.

The following options override the default ordering rules.

-d

Dictionary order: only alphanumeric and space characters (as specified by the locale in LC_CTYPE) are significant in comparisons.

NOTE: This option is silently enforced in all locales except the C locale and cannot be overridden.

-f

Fold lowercase letters into uppercase (as specified by the locale in LC_CTYPE).

NOTE: This option is silently enforced in all locales except the C locale and cannot be overridden.

-i

Ignore non-printable characters (as specified by the locale in LC_CTYPE).

-M

Compare as months. The full abbreviation for the given locale is used, regardless of the size of the abbreviation. Month names are processed according to the locale specified in the LC_TIME environment variable (see LANG on environ(5)). For example, in an English locale the sorting order would be ``JAN'' < ``FEB'' < ... < ``DEC.'' Invalid fields compare low to ``JAN.'' The -M option implies the -b option (see below).

-n

An initial numeric string, consisting of optional blanks, an optional minus sign, and zero or more digits with an optional decimal point, is sorted by arithmetic value. The -n option implies the -b option (see below).

NOTE: The -b option is only effective when restricted sort key specifications are in effect.

-r

Reverse the sense of comparisons.

When ordering options appear before restricted sort key specifications, the requested ordering rules are applied globally to all sort keys. When attached to a specific sort key (described below), the specified ordering options override all global ordering options for that key.

The notation -k pos1,pos2 restricts a sort key to one beginning at pos1 and ending at pos2. The characters at position pos1 and pos2 are included in the sort key (provided that pos2 does not precede pos1). A missing ,pos2 means the end of the line.

The obsolescent notation +pos1 and -pos2 restricts a sort key to one beginning at pos1 and ending just before pos2. The characters at position pos1 and just before pos2 are included in the sort key, provided that pos2 does not precede pos1. So:

+m.n -o.p

is equivalent to:

   if p == 0
   	-k m+1.n+1,o.0
   if p > 0
   	-k m+1.n+1,o+1.p

All uses of -k pos1,pos2 below apply equally well to +pos1 -pos2 using the above mapping, including the flags usable in m and n. See the Example section for further clarification.

Specifying pos1 and pos2 involves the notion of a field, a minimal sequence of characters followed by a field separator or a newline. By default, the first blank (space or tab) of a sequence of blanks acts as the field separator. All blanks in a sequence of blanks are considered to be part of the next field; for example, all blanks at the beginning of a line are considered to be part of the first field. The treatment of field separators can be altered using the options:

-b: Ignore leading blanks when determining the starting and ending positions of a restricted sort key. (Single-byte blanks only.) If the -b option is specified before the first -k argument, it will be applied to all those arguments. Otherwise, the b flag may be attached independently to each posn in -k pos1,pos2 argument (see below).
-t x: Use x as the field separator character; x is not considered to be part of a field (although it may be included in a sort key). Each occurrence of x is significant (for example, xx delimits an empty field). x may be a supplementary code set character.

pos1 and pos2 each have the form m.n optionally followed by one or more of the flags bdfiMnr. A starting position specified by -k m.n is interpreted to mean the nth character in the mth field A missing .n means .1 indicating the first character of the mth field. If the b flag is in effect n is counted from the first non-blank in the mth field; -k m.1b refers to the first non-blank character in the mth field.

A last position specified by -k . . . ,m.n is interpreted to mean the nth character (including separators) of the mth field. A missing .n means .0, indicating the last character of the mth field. If the b flag is in effect n is counted from the character after the last leading blank in the mth field; -k . . . ,m.1b refers to the first non-blank in the mth field.

The b flag affects only the posn that it is attached to. The other flags (dfiMnr) can be attached to either pos1 or pos2 or both, and always affect both specifiers.

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.

Examples

Sort the contents of infile with the second field as the sort key:

sort -k 2,2 infile

Sort, in reverse order, the contents of infile1 and infile2, placing the output in outfile and using the first character of the second field as the sort key:

sort -r -o outfile -k 2.1,2.1 infile1 infile2

Sort, in reverse order, the contents of infile1 and infile2 using the first non-blank character of the second field as the sort key:

sort -r -k 2.1b,2.1b infile1 infile2

Print the password file ( passwd(4)) sorted by the numeric user ID (the third colon-separated field):

sort -t : -k 3,3n /etc/passwd

Sort the contents of the password file using the group ID (fourth field) as the primary sort key and the user ID (third field) as the secondary sort key:

sort -t : -k 4,4 -k 3,3 /etc/passwd

Print the lines of the already sorted file infile, suppressing all but the first occurrence of lines having the same third field (the options -um with just one input file make the choice of a unique representative from a set of equal lines predictable):

sort -um -k 3,3 infile

Files

/var/tmp/stm???: temporary sort files; see ``Notices''
/usr/lib/locale/locale/LC_MESSAGES/uxcore.abi: language-specific message file (See LANG on environ(5).)

References

comm(1), join(1), uniq(1)

Notices

sort comments and exits with non-zero status for various trouble conditions (for example, when input lines are too long), and for disorder discovered under the -c option.

When the last line of an input file is missing a newline character, sort appends one, prints a warning message, and continues. sort does not guarantee preservation of relative line ordering on equal keys.

The +pos and -pos options are becoming obsolete due to POSIX. Application writers should avoid using them.

Use the POSIX2 environment variable to get POSIX.2 behavior. This behvior is inconsistent with existing System V behavior.

In the United States, when installing a UnixWare system, be sure to set LANG= to the default ``C''. If it is set to ``United States'', corruption of scripts occurs and the output of alphabetic sort commands (such as sort or ls) becomes case sensitive.

*TMPDIR=tmpdir* export TMPDIR sort largefile**	sort -T *tmpdir* largefile
If the *tmpdir* you specify does not exist, sort will use
/tmp to store temporary files.