sort(1)

Sorts on a byte-by-byte basis using each character's encoded value. On some systems, extended characters will be considered negative values, and so sort before ASCII characters. If you are sorting ASCII characters in a non-C/POSIX locale, this flag performs much faster.

Check that the single input file is sorted according to the ordering rules. No output is produced; the exit code is set to indicate the result.

Merge only; the input files are assumed to be already sorted.

The argument given is the name of an output file to use instead of the standard output. This file can be the same as one of the input files.

Unique: suppress all but one in each set of lines having equal keys. If used with the -c option, check to see that there are no lines with duplicate keys, in addition to checking that the input file is sorted.

The amount of main memory used by the sort can have a large impact on its performance. 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 starts 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, -y 0 is guaranteed to start with minimum memory. By convention, -y (with no argument) starts with maximum memory.

The size of the longest line read is recorded in the sort phase so that 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.

Use dir as the directory for temporary scratch files rather than the default directory, which is is one of the following, tried in order: the directory as specified in the TMPDIR environment variable; /var/tmp, and finally, /tmp.

Quasi-dictionary order: only alphanumeric characters and blanks (spaces and tabs), as defined by LC_CTYPE are significant in comparisons (see environ(5)).

(UNIX Standard only, see standards(5)) The behavior is undefined for a sort key to which -i or -n also applies.

Fold letters. Prior to being compared, all lowercase letters are effectively converted into their uppercase equivalents, as defined by LC_CTYPE.

In non-numeric comparisons, ignore all characters which are non-printable, as defined by LC_CTYPE. For the ASCII character set, octal character codes 001 through 037 and 0177 are ignored.

The sort key is restricted to an initial numeric string consisting of optional blanks, an optional minus sign, zero or more digits with optional radix character, and optional thousands separators. The radix and thousands separator characters are defined by LC_NUMERIC. The field is sorted by arithmetic value. An empty (missing) numeric field is treated as arithmetic zero. Leading zeros and plus or minus signs on zeros do not affect the ordering. The -n option implies the -b option (see below).

Reverse the sense of comparisons.

Compare as months. The first several non-blank characters of the field are folded to uppercase and compared with the langinfo(5) items ABMON_1 < ABMON_2 < ... < ABMON_12. An invalid field is treated as being less than ABMON_1 string. For example, American month names are compared such that JAN < FEB < ... < DEC. An invalid field is treated as being less than all months. The -M option implies the -b option (see below).

Use char as the field separator character; char is not considered to be part of a field (although it can be included in a sort key). Each occurrence of char is significant (for example, <char><char> delimits an empty field). If -t is not specified, <blank> characters will be used as default field separators; each maximal sequence of <blank> characters that follows a non-<blank> character is a field separator.

Ignore leading blanks when determining the starting and ending positions of a restricted sort key. If the -b option is specified before the first -k option (+ pos1 argument), it is applied to all -k options (+ pos1 arguments). Otherwise, the -b option can be attached independently to each -k field_start or field_end option (+ pos1 or (- pos2 argument; see below). Note that the -b option is only effective when restricted sort key specifications are given.

The keydef argument defines a restricted sort key. The format of this definition is

which defines a key field beginning at field_start and ending at field_end. The characters at positions field_start and field_end are included in the key field, providing that field_end does not precede field_start. A missing field_end means the end of the line. Fields and characters within fields are numbered starting with 1. Note that this is different than the obsolete form of restricted sort keys, where numbering starts at 0. See WARNINGS below.

Specifying field_start and field_end involves the notion of a field, a minimal sequence of characters followed by a field separator or a new-line. By default, the first blank 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 arguments field_start and field_end each have the form m.n which are optionally followed by one or more of the type options b, d, f, i, n, r, or M. These modifiers have the functionality for this key only, that their command-line counterparts have for the entire record.

A field_start position specified by 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 option is in effect, n is counted from the first non-blank character in the mth field.

A field_end position specified by m.n is interpreted to mean the nth character in the mth field. If n is missing, the mth field ends at the last character of the field. If the -b option is in effect, n is counted from the first non-<blank> character in the mth field.

Multiple -k options are permitted and are significant in command line order. A maximum of 9 -k options can be given. If no -k option is specified, a default sort key of the entire line is used. 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. If all the specified keys compare equal, the entire record is used as the final key.

The -k option is intended to replace the obsolete [+ pos1 [+ pos2]] notation, using field_start and field_end respectively. The fully specified [+ pos1 [+ pos2]] form:

is equivalent to: