NAME
sort —
sort or merge text files
SYNOPSIS
sort |
[-bdfHilmnrSsu]
[-k
kstart[, kend]]
[-o
output]
[-R char]
[-T dir]
[-t char]
[file ...] |
sort |
-C|-c
[-bdfilnru]
[-k
kstart[, kend]
[-t
char]]
[-R char]
[file] |
DESCRIPTION
The
sort utility sorts text files by lines. Comparisons are
based on one or more sort keys extracted from each line of input, and are
performed lexicographically. By default, if keys are not given,
sort regards each input line as a single field.
The following options are available:
-
-
- -C
- Identical to -c without the error
messages in the case of unsorted input.
-
-
- -c
- Check that the single input file is sorted. If the file is
not sorted, sort produces the appropriate error messages
and exits with code 1; otherwise, sort returns 0.
sort -c produces no output. See also
-u.
-
-
- -H
- Ignored for compatibility with earlier versions of
sort.
-
-
- -m
- Merge only; the input files are assumed to be
pre-sorted.
-
-
- -o
output
- The argument given is the name of an
output file to be used instead of the standard
output. This file can be the same as one of the input files.
-
-
- -S
- Don't use stable sort. Default is to use stable sort.
-
-
- -s
- Use stable sort, keeps records with equal keys in their
original order. This is the default. Provided for compatibility with other
sort implementations only.
-
-
- -T
dir
- Use dir as the directory for
temporary files. The default is the value specified in the environment
variable
TMPDIR or
/tmp if
TMPDIR
is not defined.
-
-
- -u
- Unique: suppress all but one in each set of lines having
equal keys. If used with the -c option, check that there
are no lines with duplicate keys.
The following options, which should be given before any
-k
options, override the default ordering rules. When ordering options appear
independent of, and before, key field specifications, the requested field
ordering rules are applied globally to all sort keys. When attached to a
specific key (see
-k), the ordering options override all
global ordering options for that key.
-
-
- -d
- Only blank space and alphanumeric characters are used in
making comparisons.
-
-
- -f
- Considers all lowercase characters that have uppercase
equivalents to be the same for purposes of comparison.
-
-
- -i
- Ignore all non-printable characters.
-
-
- -l
- Sort by the string length of the field, not by the field
itself.
-
-
- -n
- An initial numeric string, consisting of optional blank
space, optional plus or minus sign, and zero or more digits (including
decimal point) is sorted by arithmetic value. (The -n
option no longer implies the -b option.)
-
-
- -r
- Reverse the sense of comparisons.
The treatment of field separators can be altered using these options:
-
-
- -b
- Ignores leading blank space when determining the start and
end of a restricted sort key. A -b option specified
before the first -k option applies globally to all
-k options. Otherwise, the -b option
can be attached independently to each field argument
of the -k option (see below). Note that the
-b option has no effect unless key fields are
specified.
-
-
- -k
kstart[
,
kend]
- Designates the starting position,
kstart, and optional ending position,
kend, of a key field. The -k
option replaces the obsolescent options
+pos1 and
-pos2.
-
-
- -R
char
- char is used as the record separator
character. This should be used with discretion; -R
⟨alphanumeric⟩ usually produces
undesirable results. If char is not a single character, then it specifies
the value of the desired record separator as an integer specified in any
of the normal NNN, 0ooo, or 0xXXX ways, or as an octal value preceded by
\. Caution: do not attempt to specify Ctl-A as “-R 1” which
will not do what was intended at all! The default record separator is
newline.
-
-
- -t
char
- char is used as the field separator
character. The initial char is not considered to be
part of a field when determining key offsets (see below). Each occurrence
of char is significant (for example,
“charchar” delimits an empty field). If
-t is not specified, the default field separator is a
sequence of blank-space characters, and consecutive blank spaces do
not delimit an empty field; further, the initial blank
space is considered part of a field when determining key
offsets.
The following operands are available:
-
-
- file
- The pathname of a file to be sorted, merged, or checked. If
no file operands are specified, or if a
file operand is -, the standard
input is used.
A field is defined as a minimal sequence of characters followed by a field
separator or a newline character. By default, the first blank space of a
sequence of blank spaces acts as the field separator. All blank spaces in a
sequence of blank spaces are considered as part of the next field; for
example, all blank spaces at the beginning of a line are considered to be part
of the first field.
Fields are specified by the
-k
kstart[
,kend]
argument. A missing
kend argument defaults to the end of
a line.
The arguments
kstart and
kend have
the form
m.
n and
can be followed by one or more of the letters
b,
d,
f,
i,
l,
n, and
r, which
correspond to the options discussed above. A
kstart
position specified by
m.
n
(
m,
n >
0) is interpreted as the
nth character in the
mth field. A missing
.
n in
kstart 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;
m.1b
refers to the first
non-blank character in the
mth field.
A
kend position specified by
m.
n is
interpreted as the
nth character (including separators)
of the
mth field. A missing
.
n indicates the last character
of the
mth field;
m = 0 designates
the end of a line. Thus the option
-k
v
.
x,
w.
y
is synonymous with the obsolescent option
+v-1
.
x-1-w-1.
y;
when
y is omitted,
-k
v
.
x,
w
is synonymous with
+v-1.
x-1-w+1.0
.
The obsolescent
+pos1
-pos2 option is still supported,
except for
-w.0b
, which
has no
-k equivalent.
sort compares records by comparing the key fields selected by
-k arguments, from first given to last, until discovering a
difference. If there are no
-k arguments, the whole record
is treated as a single key. After exhausting the
-k
arguments, if no difference has been found, then the result depends upon the
-u and
-S option settings. With
-u the records are considered identical, and one is
supressed. Otherwise with
-s set (default) the records are
left in their original order, or with
-S (posix mode) the
whole record is considered as a tie breaker.
ENVIRONMENT
If the following environment variable exists, it is used by
sort.
-
-
TMPDIR
- sort uses the contents of the
TMPDIR
environment variable as the path in which
to store temporary files.
FILES
- /tmp/sort.*
- Default temporary files.
- outputNUMBER
- Temporary file which is used for output if
output already exists. Once sorting is finished,
this file replaces output (via
link(2) and
unlink(2)).
EXIT STATUS
Sort exits with one of the following values:
- 0
- Normal behavior.
- 1
- On disorder (or non-uniqueness) with the
-c (or -C) option.
- 2
- An error occurred.
SEE ALSO
comm(1),
join(1),
uniq(1),
qsort(3),
radixsort(3)
HISTORY
A
sort command appeared in
Version 5
AT&T UNIX. This
sort implementation appeared in
4.4BSD and is used since
NetBSD
1.6.
BUGS
Posix requires the locale's thousands separator be ignored in numbers. It may be
faster to sort very large files in pieces and then explicitly merge them.
NOTES
This
sort has no limits on input line length (other than
imposed by available memory) or any restrictions on bytes allowed within
lines.
To protect data
sort -o calls
link(2) and
unlink(2), and thus fails on
protected directories.
Input files should be text files. If file doesn't end with record separator
(which is typically newline), the
sort utility silently
supplies one.
The current
sort uses lexicographic radix sorting, which
requires that sort keys be kept in memory (as opposed to previous versions
which used quick and merge sorts and did not.) Thus performance depends highly
on efficient choice of sort keys, and the
-b option and the
kend argument of the
-k option should
be used whenever possible. Similarly,
sort
-k1f is equivalent to
sort
-f and may take twice as long.