/usr/bin/sort [-bcdfimMnru] [-k keydef] [-o output]
 [-S kmem] [-t char] [-T directory] [-y [kmem]]
 [-z recsz] [+pos1 [-pos2]] [file]...

/usr/xpg4/bin/sort [-bcdfimMnru] [-k keydef] [-o output]
 [-S kmem] [-t char] [-T directory] [-y [kmem]]
 [-z recsz] [+pos1 [-pos2]] [file]...

The sort command sorts lines of all the named files together and writes the result on the standard output.

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. Lines are ordered according to the collating sequence of the current locale.

The following options alter the default behavior:

The default sort order depends on the value of LC_COLLATE. If LC_COLLATE is set to C, sorting is in ASCII order. If LC_COLLATE is set to en_US, sorting is case insensitive except when the two strings are otherwise equal and one has an uppercase letter earlier than the other. Other locales have other sort orders.

The following options override the default ordering rules. When ordering options appear independent of any key field specifications, the requested field ordering rules are applied globally to all sort keys. When attached to a specific key (see Sort Key Options), the specified ordering options override all global ordering options for that key. In the obsolescent forms, if one or more of these options follows a +pos1 option, it affects only the key field specified by that preceding option. -d

The treatment of field separators can be altered using the following options: -b

Sort keys can be specified using the options: -k keydef

-k field_start [type] [,field_end [type] ]

-k field_start[type][,field_end[type]]

field_number[.first_character]

field_number[.last_character]

+w.xT -y.zU

undefined (z==0 & U contains b & -t is present)
-k w+1.x+1T,y.0U (z==0 otherwise)
-k w+1.x+1T,y+1.zU (z > 0)

The following operand is supported: file

See largefile(5) for the description of the behavior of sort when encountering files greater than or equal to 2 Gbyte ( 2^31 bytes).

In the following examples, first the preferred and then the obsolete way of specifying sort keys are given as an aid to understanding the relationship between the two forms.

Example 1 Sorting with the Second Field as a sort Key

Either of the following commands sorts the contents of infile with the second field as the sort key:

example% sort -k 2,2 infile
example% sort +1 -2 infile

Example 2 Sorting in Reverse Order

Either of the following commands sorts, in reverse order, the contents of infile1 and infile2, placing the output in outfile and using the second character of the second field as the sort key (assuming that the first character of the second field is the field separator):

example% sort -r -o outfile -k 2.2,2.2 infile1 infile2
example% sort -r -o outfile +1.1 -1.2 infile1 infile2

Example 3 Sorting Using a Specified Character in One of the Files

Either of the following commands sorts the contents of infile1 and infile2 using the second non-blank character of the second field as the sort key:

example% sort -k 2.2b,2.2b infile1 infile2
example% sort +1.1b -1.2b infile1 infile2

Example 4 Sorting by Numeric User ID

Either of the following commands prints the passwd(4) file (user database) sorted by the numeric user ID (the third colon-separated field):

example% sort -t : -k 3,3n /etc/passwd
example% sort -t : +2 -3n /etc/passwd

Example 5 Printing Sorted Lines Excluding Lines that Duplicate a Field

Either of the following commands prints the lines of the already sorted file infile, suppressing all but one occurrence of lines having the same third field:

example% sort -um -k 3.1,3.0 infile
example% sort -um +2.0 -3.0 infile

Example 6 Sorting by Host IP Address

Either of the following commands prints the hosts(4) file (IPv4 hosts database), sorted by the numeric IP address (the first four numeric fields):

example$ sort -t . -k 1,1n -k 2,2n -k 3,3n -k 4,4n /etc/hosts
example$ sort -t . +0 -1n +1 -2n +2 -3n +3 -4n /etc/hosts

Since '.' is both the field delimiter and, in many locales, the decimal separator, failure to specify both ends of the field leads to results where the second field is interpreted as a fractional portion of the first, and so forth.

See environ(5) for descriptions of the following environment variables that affect the execution of sort: LANG, LC_ALL, LC_COLLATE, LC_MESSAGES, and NLSPATH. LC_CTYPE

The following exit values are returned: 0

See attributes(5) for descriptions of the following attributes:

comm(1), join(1), uniq(1), nl_langinfo(3C), strftime(3C), hosts(4), passwd(4), attributes(5), environ(5), largefile(5), standards(5)

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

When the last line of an input file is missing a new-line character, sort appends one, prints a warning message, and continues.

sort does not guarantee preservation of relative line ordering on equal keys.

One can tune sort performance for a specific scenario using the -S option. However, one should note in particular that sort has greater knowledge of how to use a finite amount of memory for sorting than the virtual memory system. Thus, a sort invoked to request an extremely large amount of memory via the -S option could perform extremely poorly.

As noted, certain of the field modifiers (such as -M and -d) cause the interpretation of input data to be done with reference to locale-specific settings. The results of this interpretation can be unexpected if one's expectations are not aligned with the conventions established by the locale. In the case of the month keys, sort does not attempt to compensate for approximate month abbreviations. The precise month abbreviations from nl_langinfo(3C) or strftime(3C) are the only ones recognized. For printable or dictionary order, if these concepts are not well-defined by the locale, an empty sort key might be the result, leading to the next key being the significant one for determining the appropriate ordering.