sort(1)
Name
sort − sort file data
Syntax
sort [options] [−k keydef] [+pos1[−pos2]] [file...]
Description
The sort command 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.
Options
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.
−bIgnores leading blanks (spaces and tabs) in field comparisons.
−dSorts data according to dictionary ordering: letters, digits, and blanks only.
−fFolds uppercase to lowercase while sorting.
−iIgnore characters outside the ASCII range 040-0176 in nonnumeric comparisons.
−k keydefThe keydefargument is a key field definition. The format is field_start, [field_end] [type], where field_start and field_end are the definition of the restricted search key, and type is a modifier from the option list [bdfinr]. These modifiers have the functionality, for this key only, that their command line counter-parts have for the entire record.
−nSorts fields with numbers numerically. 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 taken to be equal to 0.) Option n implies option b.
−rReverses the sense of comparisons.
−txUses specified character as field separator.
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 options 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 options 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 are additional options:
−cChecks sorting order and displays output only if out of order.
−mMerges previously sorted data.
−onameUses specified file as output file. This file may be the same as one of the inputs.
−T
Uses specified directory to build temporary files.
−u
Suppresses all duplicate entries. 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, 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
Restrictions
Very long lines are silently truncated.
Diagnostics
Comments and exits with nonzero status for various trouble conditions and for disorder discovered under option c.
Files
/usr/tmp/stm*, /tmp/*first and second tries for temporary files