NAME
sort
- sort or merge text files
SYNOPSIS
sort
[-bcdfHimnrSsu]
field1[
,
field2]
[-k]
[-o output]
[-R char]
[-T dir]
[-t char]
[]
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
-
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.
- -H
-
Ignored for compatibility with earlier versions of
.
- -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 override the default ordering rules.
When ordering options appear independent of 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.
- -n
-
An initial numeric string, consisting of optional blank space, optional
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.
- -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.
- -R char
-
char
is used as the record separator character.
This should be used with discretion;
-R <alphanumeric>
usually produces undesirable results.
The default record separator is newline.
- -k field1[
,
field2] -
Designates the starting position,
field1,
and optional ending position,
field2,
of a key field.
The
-k
option replaces the obsolescent options
+pos1
and
-pos2.
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
field1[,field2]
argument.
A missing
field2
argument defaults to the end of a line.
The arguments
field1
and
field2
have the form
m
.
n
and can be followed by one or more of the letters
b, d, f, i,
n,
and
r,
which correspond to the options discussed above.
A
field1
position specified by
m
.
n
(m, n > 0)
is interpreted as the
nth
character in the
mth
field.
A missing
.
n
in
field1
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
field2
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.
RETURN VALUES
Sort exits with one of the following values:
- 0
-
Normal behavior.
- 1
-
On disorder (or non-uniqueness) with the
-c
option
- 2
-
An error occurred.
ENVIRONMENT
If the following environment variable exists, it is used by
.
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)).
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
NetBSD1.6.
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
field2
argument of the
-k
option should be used whenever possible.
Similarly,
sort
-k1f
is equivalent to
sort
-f
and may take twice as long.