sort(1)
- NetBSD Manual Pages
SORT(1) SORT(1)
NAME
sort - sort lines of text files
SYNOPSIS
sort [-cmus] [-t separator] [-o output-file] [-bdfiMnr]
[+POS1 [-POS2]] [-k POS1[,POS2]] [file...]
DESCRIPTION
This manual page documents the GNU version of sort. sort
sorts, merges, or compares all the lines from the given
files, or the standard input if no files are given. A
file name of `-' means standard input. By default, sort
writes the results to the standard output.
sort has three modes of operation: sort (the default),
merge, and check for sortedness. The following options
change the operation mode:
-c Check whether the given files are already sorted:
if they are not all sorted, print an error message
and exit with a status of 1.
-m Merge the given files by sorting them as a group.
Each input file should already be individually
sorted. It always works to sort instead of merge;
merging is provided because it is faster, in the
case where it works.
A pair of lines is compared as follows: if any key fields
have been specified, sort compares each pair of fields, in
the order specified on the command line, according to the
associated ordering options, until a difference is found
or no fields are left.
If any of the global options Mbdfinr are given but no key
fields are specified, sort compares the entire lines
according to the global options.
Finally, as a last resort when all keys compare equal (or
if no ordering options were specified at all), sort com-
pares the lines byte by byte in machine collating
sequence. The -s option disables this last resort compar-
ison, producing a stable sort.
GNU sort has no limits on input line length or restric-
tions on bytes allowed within lines. In addition, if the
final byte of an input file is not a newline, GNU sort
silently supplies one. In some cases, such as exactly
what the -b and -f options do, BSD and System V sort pro-
grams produce different output; GNU sort follows the POSIX
behavior, which is usually like the System V behavior.
If the environment variable TMPDIR is set, sort uses it as
the directory in which to put temporary files instead of
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SORT(1) SORT(1)
the default, /tmp.
The following options affect the ordering of output lines.
They may be specified globally or as part of a specific
key field. If no key fields are specified, global options
apply to comparison of entire lines; otherwise the global
options are inherited by key fields that do not specify
any special options of their own.
-b Ignore leading blanks when finding sort keys in
each line.
-d Sort in `dictionary order': ignore all characters
except letters, digits and blanks when sorting.
-f Fold lower case characters into the equivalent
upper case characters when sorting so that, for
example, `b' is sorted the same way `B' is.
-i Ignore characters outside the ASCII range 040-0176
(inclusive) when sorting.
-M An initial string, consisting of any amount of
white space, followed by three letters abbreviating
a month name, is folded to lower case and compared
in the order `jan' < `feb' < ... < `dec.' Invalid
names compare low to valid names. This option
implies -b.
-n Compare according to arithmetic value an initial
numeric string consisting of optional white space,
an optional - sign, and zero or more digits,
optionally followed by a decimal point and zero or
more digits. This option implies -b.
-r Reverse the result of comparison, so that lines
with greater key values appear earlier in the out-
put instead of later.
Other options are:
-o output-file
Write output to output-file instead of to the stan-
dard output. If output-file is one of the input
files, sort copies it to a temporary file before
sorting and writing the output to output-file.
-t separator
Use character separator as the field separator when
finding the sort keys in each line. By default,
fields are separated by the empty string between a
non-whitespace character and a whitespace charac-
ter. That is to say, given the input line ` foo
bar', sort breaks it into fields ` foo' and ` bar'.
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SORT(1) SORT(1)
The field separator is not considered to be part of
either the field preceding or the field following
it.
-u For the default case or the -m option, only output
the first of a sequence of lines that compare
equal. For the -c option, check that no pair of
consecutive lines compares equal.
+POS1 [-POS2]
Specify a field within each line to use as a sort-
ing key. The field consists of the portion of the
line starting at POS1 and up to (but not including)
POS2 (or to the end of the line if POS2 is not
given). The fields and character positions are
numbered starting with 0.
-k POS1[,POS2]
An alternative syntax for specifying sorting keys.
The fields and character positions are numbered
starting with 1.
A position has the form f.c, where f is the number of the
field to use and c is the number of the first character
from the beginning of the field (for +pos) or from the end
of the previous field (for -pos). The .c part of a posi-
tion may be omitted in which case it is taken to be the
first character in the field. If the -b option has been
given, the .c part of a field specification is counted
from the first nonblank character of the field (for +pos)
or from the first nonblank character following the previ-
ous field (for -pos).
A +pos or -pos argument may also have any of the option
letters Mbdfinr appended to it, in which case the global
ordering options are not used for that particular field.
The -b option may be independently attached to either or
both of the +pos and -pos parts of a field specification,
and if it is inherited from the global options it will be
attached to both. If a -n or -M option is used, thus
implying a -b option, the -b option is taken to apply to
both the +pos and the -pos parts of a key specification.
Keys may span multiple fields.
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