Originální popis anglicky:
sort - sort, merge, or sequence check text files
Návod, kniha: POSIX Programmer's Manual
sort [-m][-o
output][-bdfinru ][-t
char][-k keydef]...
[file ...]
sort -c
[-bdfinru][-t
char ][-k
keydef][file]
The
sort utility shall perform one of the following functions:
- 1.
- Sort lines of all the named files together and write the
result to the specified output.
- 2.
- Merge lines of all the named (presorted) files together and
write the result to the specified output.
- 3.
- Check that a single input file is correctly presorted.
Comparisons shall be based on one or more sort keys extracted from each line of
input (or, if no sort keys are specified, the entire line up to, but not
including, the terminating <newline>), and shall be performed using the
collating sequence of the current locale.
The
sort utility shall conform to the Base Definitions volume of
IEEE Std 1003.1-2001, Section 12.2, Utility Syntax Guidelines,
and the
-k keydef option should follow the
-b,
-d,
-f,
-i,
-n, and
-r options.
The following options shall be supported:
- -c
- Check that the single input file is ordered as specified by
the arguments and the collating sequence of the current locale. No output
shall be produced; only the exit code shall be affected.
- -m
- Merge only; the input file shall be assumed to be already
sorted.
- -o output
- Specify 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.
- -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, in addition to checking that the input file is
sorted.
The following options shall override the default ordering rules. When ordering
options appear independent of any key field specifications, the requested
field ordering rules shall be applied globally to all sort keys. When attached
to a specific key (see
-k), the specified ordering options shall
override all global ordering options for that key.
- -d
- Specify that only <blank>s and alphanumeric
characters, according to the current setting of LC_CTYPE , shall be
significant in comparisons. The behavior is undefined for a sort key to
which -i or -n also applies.
- -f
- Consider all lowercase characters that have uppercase
equivalents, according to the current setting of LC_CTYPE , to be
the uppercase equivalent for the purposes of comparison.
- -i
- Ignore all characters that are non-printable, according to
the current setting of LC_CTYPE .
- -n
- Restrict the sort key to an initial numeric string,
consisting of optional <blank>s, optional minus sign, and zero or
more digits with an optional radix character and thousands separators (as
defined in the current locale), which shall be sorted by arithmetic value.
An empty digit string shall be treated as zero. Leading zeros and signs on
zeros shall not affect ordering.
- -r
- Reverse the sense of comparisons.
The treatment of field separators can be altered using the options:
- -b
- Ignore leading <blank>s when determining the starting
and ending positions of a restricted sort key. If the -b option is
specified before the first -k option, it shall be applied to all
-k options. Otherwise, the -b option can be attached
independently to each -k field_start or field_end
option-argument (see below).
- -t char
- Use char as the field separator character;
char shall not be considered to be part of a field (although it can
be included in a sort key). Each occurrence of char shall be
significant (for example, < char><char> delimits
an empty field). If -t is not specified, <blank>s shall be
used as default field separators; each maximal non-empty sequence of
<blank>s that follows a non- <blank> shall be a field
separator.
Sort keys can be specified using the options:
- -k keydef
- The keydef argument is a restricted sort key field
definition. The format of this definition is:
field_start[type][,field_end[type]]
where
field_start and
field_end define a key field restricted to a
portion of the line (see the EXTENDED DESCRIPTION section), and
type is
a modifier from the list of characters
'b' ,
'd' ,
'f' ,
'i' ,
'n' ,
'r' . The
'b' modifier shall behave
like the
-b option, but shall apply only to the
field_start or
field_end to which it is attached. The other modifiers shall behave
like the corresponding options, but shall apply only to the key field to which
they are attached; they shall have this effect if specified with
field_start,
field_end, or both. If any modifier is attached to
a
field_start or to a
field_end, no option shall apply to
either. Implementations shall support at least nine occurrences of the
-k option, which shall be significant in command line order. If no
-k option is specified, a default sort key of the entire line shall be
used.
When there are multiple key fields, later keys shall be compared only after all
earlier keys compare equal. Except when the
-u option is specified,
lines that otherwise compare equal shall be ordered as if none of the options
-d,
-f,
-i,
-n, or
-k were present (but
with
-r still in effect, if it was specified) and with all bytes in the
lines significant to the comparison. The order in which lines that still
compare equal are written is unspecified.
The following operand shall be supported:
- file
- A 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 shall be used.
The standard input shall be used only if no
file operands are specified,
or if a
file operand is
'-' . See the INPUT FILES section.
The input files shall be text files, except that the
sort utility shall
add a <newline> to the end of a file ending with an incomplete last
line.
The following environment variables shall affect the execution of
sort:
- LANG
- Provide a default value for the internationalization
variables that are unset or null. (See the Base Definitions volume of
IEEE Std 1003.1-2001, Section 8.2, Internationalization
Variables for the precedence of internationalization variables used to
determine the values of locale categories.)
- LC_ALL
- If set to a non-empty string value, override the values of
all the other internationalization variables.
- LC_COLLATE
-
Determine the locale for ordering rules.
- LC_CTYPE
- Determine the locale for the interpretation of sequences of
bytes of text data as characters (for example, single-byte as opposed to
multi-byte characters in arguments and input files) and the behavior of
character classification for the -b, -d, -f,
-i, and -n options.
- LC_MESSAGES
- Determine the locale that should be used to affect the
format and contents of diagnostic messages written to standard error.
- LC_NUMERIC
-
Determine the locale for the definition of the radix character and thousands
separator for the -n option.
- NLSPATH
- Determine the location of message catalogs for the
processing of LC_MESSAGES .
Default.
Unless the
-o or
-c options are in effect, the standard output
shall contain the sorted input.
The standard error shall be used for diagnostic messages. A warning message
about correcting an incomplete last line of an input file may be generated,
but need not affect the final exit status.
If the
-o option is in effect, the sorted input shall be written to the
file
output.
The notation:
-k field_start[type][,field_end[type]]
shall define a key field that begins at
field_start and ends at
field_end inclusive, unless
field_start falls beyond the end of
the line or after
field_end, in which case the key field is empty. A
missing
field_end shall mean the last character of the line.
A field comprises a maximal sequence of non-separating characters and, in the
absence of option
-t, any preceding field separator.
The
field_start portion of the
keydef option-argument shall have
the form:
field_number[.first_character]
Fields and characters within fields shall be numbered starting with 1. The
field_number and
first_character pieces, interpreted as positive
decimal integers, shall specify the first character to be used as part of a
sort key. If
.first_character is omitted, it shall refer to the first
character of the field.
The
field_end portion of the
keydef option-argument shall have the
form:
field_number[.last_character]
The
field_number shall be as described above for
field_start. The
last_character piece, interpreted as a non-negative decimal integer,
shall specify the last character to be used as part of the sort key. If
last_character evaluates to zero or
.last_character is omitted,
it shall refer to the last character of the field specified by
field_number.
If the
-b option or
b type modifier is in effect, characters
within a field shall be counted from the first non- <blank> in the
field. (This shall apply separately to
first_character and
last_character.)
The following exit values shall be returned:
- 0
- All input files were output successfully, or -c was
specified and the input file was correctly sorted.
- 1
- Under the -c option, the file was not ordered as
specified, or if the -c and -u options were both specified,
two input lines were found with equal keys.
- >1
- An error occurred.
Default.
The following sections are informative.
The default value for
-t, <blank>, has different properties from,
for example,
-t "<space>". If a line contains:
the following treatment would occur with default separation as opposed to
specifically selecting a <space>:
| Field |
Default |
-t "<space>" |
| 1 |
<space><space>foo |
empty |
| 2 |
empty |
empty |
| 3 |
empty |
foo |
The leading field separator itself is included in a field when
-t is not
used. For example, this command returns an exit status of zero, meaning the
input was already sorted:
sort -c -k 2 <<eof
y<tab>b
x<space>a
eof
(assuming that a <tab> precedes the <space> in the current collating
sequence). The field separator is not included in a field when it is
explicitly set via
-t. This is historical practice and allows usage
such as:
sort -t "|" -k 2n <<eof
Atlanta|425022|Georgia
Birmingham|284413|Alabama
Columbia|100385|South Carolina
eof
where the second field can be correctly sorted numerically without regard to the
non-numeric field separator.
The wording in the OPTIONS section clarifies that the
-b,
-d,
-f,
-i,
-n, and
-r options have to come before the
first sort key specified if they are intended to apply to all specified keys.
The way it is described in this volume of IEEE Std 1003.1-2001
matches historical practice, not historical documentation. The results are
unspecified if these options are specified after a
-k option.
The
-f option might not work as expected in locales where there is not a
one-to-one mapping between an uppercase and a lowercase letter.
- 1.
- The following command sorts the contents of infile
with the second field as the sort key:
- 2.
- The following command 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):
sort -r -o outfile -k 2.2,2.2 infile1 infile2
- 3.
- The following command sorts the contents of infile1
and infile2 using the second non- <blank> of the second field
as the sort key:
sort -k 2.2b,2.2b infile1 infile2
- 4.
- The following command prints the System V password
file (user database) sorted by the numeric user ID (the third
colon-separated field):
sort -t : -k 3,3n /etc/passwd
- 5.
- The following command prints the lines of the already
sorted file infile, suppressing all but one occurrence of lines
having the same third field:
sort -um -k 3.1,3.0 infile
Examples in some historical documentation state that options
-um with one
input file keep the first in each set of lines with equal keys. This behavior
was deemed to be an implementation artifact and was not standardized.
The
-z option was omitted; it is not standard practice on most systems
and is inconsistent with using
sort to sort several files individually
and then merge them together. The text concerning
-z in historical
documentation appeared to require implementations to determine the proper
buffer length during the sort phase of operation, but not during the merge.
The
-y option was omitted because of non-portability. The
-M
option, present in System V, was omitted because of non-portability in
international usage.
An undocumented
-T option exists in some implementations. It is used to
specify a directory for intermediate files. Implementations are encouraged to
support the use of the
TMPDIR environment variable instead of adding an
option to support this functionality.
The
-k option was added to satisfy two objections. First, the zero-based
counting used by
sort is not consistent with other utility conventions.
Second, it did not meet syntax guideline requirements.
Historical documentation indicates that "setting
-n implies
-b". The description of
-n already states that optional
leading <blank>s are tolerated in doing the comparison. If
-b is
enabled, rather than implied, by
-n, this has unusual side effects.
When a character offset is used in a column of numbers (for example, to sort
modulo 100), that offset is measured relative to the most significant digit,
not to the column. Based upon a recommendation from the author of the original
sort utility, the
-b implication has been omitted from this
volume of IEEE Std 1003.1-2001, and an application wishing to
achieve the previously mentioned side effects has to code the
-b flag
explicitly.
None.
comm ,
join ,
uniq , the System Interfaces volume of
IEEE Std 1003.1-2001,
toupper()
Portions of this text are reprinted and reproduced in electronic form from IEEE
Std 1003.1, 2003 Edition, Standard for Information Technology -- Portable
Operating System Interface (POSIX), The Open Group Base Specifications Issue
6, Copyright (C) 2001-2003 by the Institute of Electrical and Electronics
Engineers, Inc and The Open Group. In the event of any discrepancy between
this version and the original IEEE and The Open Group Standard, the original
IEEE and The Open Group Standard is the referee document. The original
Standard can be obtained online at http://www.opengroup.org/unix/online.html
.
