[ < ] | [ > ] | [ << ] | [ Up ] | [ >> ] | [Top] | [Contents] | [Index] | [ ? ] |
These commands work with (or produce) sorted files.
7.1 sort
: Sort text filesSort text files. 7.2 uniq
: Uniquify filesUniquify files. 7.3 comm
: Compare two sorted files line by lineCompare two sorted files line by line. 7.5 ptx
: Produce permuted indexesProduce a permuted index of file contents. 7.4 tsort
: Topological sortTopological sort.
[ < ] | [ > ] | [ << ] | [ Up ] | [ >> ] | [Top] | [Contents] | [Index] | [ ? ] |
sort
: Sort text files
sort
sorts, merges, or compares all the lines from the given
files, or standard input if none are given or for a file of
`-'. By default, sort
writes the results to standard
output. Synopsis:
sort [option]... [file]... |
sort
has three modes of operation: sort (the default), merge,
and check for sortedness. The following options change the operation
mode:
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.
Unless otherwise specified, all comparisons use the character
collating sequence specified by the LC_COLLATE
locale.
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
compares the entire
lines. The last resort comparison
honors the `-r' global option. The `-s' (stable) option
disables this last-resort comparison so that lines in which all fields
compare equal are left in their original relative order. If no fields
or global options are specified, `-s' has no effect.
GNU sort
(as specified for all GNU utilities) has no limits on
input line length or restrictions on bytes allowed within lines. In
addition, if the final byte of an input file is not a newline, GNU
sort
silently supplies one. A line's trailing newline is part of
the line for comparison purposes; for example, with no options in an
ASCII locale, a line starting with a tab sorts before an empty line
because tab precedes newline in the ASCII collating sequence.
Upon any error, sort
exits with a status of `2'.
If the environment variable TMPDIR
is set, sort
uses its
value as the directory for temporary files instead of `/tmp'. The
`-T tempdir' option in turn overrides the environment
variable.
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. The `-b', `-d',
`-f' and `-i' options classify characters according to
the LC_CTYPE
locale.
strtod
to convert
a prefix of each line to a double-precision floating point number.
This allows floating point numbers to be specified in scientific notation,
like 1.0e-34
and 10e100
.
Do not report overflow, underflow, or conversion errors.
Use the following collating sequence:
Use this option only if there is no alternative; it is much slower than `-n' and it can lose information when converting to floating point.
LC_TIME
locale
determines the month spellings.
LC_NUMERIC
locale specifies the radix character and thousands separator.
sort -n
uses what might be considered an unconventional method
to compare strings representing floating point numbers. Rather than
first converting each string to the C double
type and then
comparing those values, sort aligns the radix characters in the two
strings and compares the strings a character at a time. One benefit
of using this approach is its speed. In practice this is much more
efficient than performing the two corresponding string-to-double (or even
string-to-integer) conversions and then comparing doubles. In addition,
there is no corresponding loss of precision. Converting each string to
double
before comparison would limit precision to about 16 digits
on most systems.
Neither a leading `+' nor exponential notation is recognized. To compare such strings numerically, use the `-g' option.
Other options are:
sort
copies
it to a temporary file before sorting and writing the output to
output-file.
sort
breaks it
into fields ` foo' and ` bar'. The field separator is
not considered to be part of either the field preceding or the field
following.
In addition, when GNU sort
is invoked with exactly one argument,
options `--help' and `--version' are recognized. See section 2. Common options.
Historical (BSD and System V) implementations of sort
have
differed in their interpretation of some options, particularly
`-b', `-f', and `-n'. GNU sort follows the POSIX
behavior, which is usually (but not always!) like the System V behavior.
According to POSIX, `-n' no longer implies `-b'. For
consistency, `-M' has been changed in the same way. This may
affect the meaning of character positions in field specifications in
obscure cases. The only fix is to add an explicit `-b'.
A position in a sort field specified with the `-k' or `+' option 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'). If the `.c' is omitted, it is taken to be the first character in the field. If the `-b' option was specified, 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 previous field (for `-pos').
A sort key option 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. Keys may span multiple fields.
Here are some examples to illustrate various combinations of options. In them, the POSIX `-k' option is used to specify sort keys rather than the obsolete `+pos1-pos2' syntax.
sort -nr |
Sort alphabetically, omitting the first and second fields. This uses a single key composed of the characters beginning at the start of field three and extending to the end of each line.
sort -k3 |
sort -t : -k 2,2n -k 5.3,5.4 |
Note that if you had written `-k 2' instead of `-k 2,2' `sort' would have used all characters beginning in the second field and extending to the end of the line as the primary numeric key. For the large majority of applications, treating keys spanning more than one field as numeric will not do what you expect.
Also note that the `n' modifier was applied to the field-end specifier for the first key. It would have been equivalent to specify `-k 2n,2' or `-k 2n,2n'. All modifiers except `b' apply to the associated field, regardless of whether the modifier character is attached to the field-start and/or the field-end part of the key specifier.
sort -t : -k 5b,5 -k 3,3n /etc/passwd |
An alternative is to use the global numeric modifier `-n'.
sort -t : -n -k 5b,5 -k 3,3 /etc/passwd |
find src -type f -print0 | sort -t / -z -f | xargs -0 etags --append |
The use of `-print0', `-z', and `-0' in this case mean that pathnames that contain Line Feed characters will not get broken up by the sort operation.
Finally, to ignore both leading and trailing white space, you could have applied the `b' modifier to the field-end specifier for the first key,
sort -t : -n -k 5b,5b -k 3,3 /etc/passwd |
or by using the global `-b' modifier instead of `-n' and an explicit `n' with the second key specifier.
sort -t : -b -k 5,5 -k 3,3n /etc/passwd |
[ < ] | [ > ] | [ << ] | [ Up ] | [ >> ] | [Top] | [Contents] | [Index] | [ ? ] |
uniq
: Uniquify files
uniq
writes the unique lines in the given `input', or
standard input if nothing is given or for an input name of
`-'. Synopsis:
uniq [option]... [input [output]] |
By default, uniq
prints the unique lines in a sorted file, i.e.,
discards all but one of identical successive lines. Optionally, it can
instead show only lines that appear exactly once, or lines that appear
more than once.
The input must be sorted. If your input is not sorted, perhaps you want
to use sort -u
.
If no output file is specified, uniq
writes to standard
output.
The program accepts the following options. Also see 2. Common options.
[ < ] | [ > ] | [ << ] | [ Up ] | [ >> ] | [Top] | [Contents] | [Index] | [ ? ] |
comm
: Compare two sorted files line by line
comm
writes to standard output lines that are common, and lines
that are unique, to two input files; a file name of `-' means
standard input. Synopsis:
comm [option]... file1 file2 |
Before comm
can be used, the input files must be sorted using the
collating sequence specified by the LC_COLLATE
locale, with
trailing newlines significant. If an input file ends in a non-newline
character, a newline is silently appended. The sort
command with
no options always outputs a file that is suitable input to comm
.
With no options, comm
produces three column output. Column one
contains lines unique to file1, column two contains lines unique
to file2, and column three contains lines common to both files.
Columns are separated by a single TAB character.
The options `-1', `-2', and `-3' suppress printing of the corresponding columns. Also see 2. Common options.
Unlike some other comparison utilities, comm
has an exit
status that does not depend on the result of the comparison.
Upon normal completion comm
produces an exit code of zero.
If there is an error it exits with nonzero status.
[ < ] | [ > ] | [ << ] | [ Up ] | [ >> ] | [Top] | [Contents] | [Index] | [ ? ] |
tsort
: Topological sort
tsort
performs a topological sort on the given file, or
standard input if no input file is given or for a file of
`-'. Synopsis:
tsort [option] [file] |
tsort
reads its input as pairs of strings, separated by blanks,
indicating a partial ordering. The output is a total ordering that
corresponds to the given partial ordering.
For example
tsort <<EOF a b c d e f b c d e EOF |
will produce the output
a b c d e f |
tsort
will detect cycles in the input and writes the first cycle
encountered to standard error.
Note that for a given partial ordering, generally there is no unique total ordering.
The only options are `--help' and `--version'. See section 2. Common options.
[ < ] | [ > ] | [ << ] | [ Up ] | [ >> ] | [Top] | [Contents] | [Index] | [ ? ] |
ptx
: Produce permuted indexes
ptx
reads a text file and essentially produces a permuted index, with
each keyword in its context. The calling sketch is either one of:
ptx [option ...] [file ...] ptx -G [option ...] [input [output]] |
The `-G' (or its equivalent: `--traditional') option disables
all GNU extensions and revert to traditional mode, thus introducing some
limitations, and changes several of the program's default option values.
When `-G' is not specified, GNU extensions are always enabled. GNU
extensions to ptx
are documented wherever appropriate in this
document. For the full list, see See section 7.5.5 The GNU extensions to ptx
.
Individual options are explained in incoming sections.
When GNU extensions are enabled, there may be zero, one or several file after the options. If there is no file, the program reads the standard input. If there is one or several file, they give the name of input files which are all read in turn, as if all the input files were concatenated. However, there is a full contextual break between each file and, when automatic referencing is requested, file names and line numbers refer to individual text input files. In all cases, the program produces the permuted index onto the standard output.
When GNU extensions are not enabled, that is, when the program
operates in traditional mode, there may be zero, one or two parameters
besides the options. If there is no parameters, the program reads the
standard input and produces the permuted index onto the standard output.
If there is only one parameter, it names the text input to be read
instead of the standard input. If two parameters are given, they give
respectively the name of the input file to read and the name of
the output file to produce. Be very careful to note that,
in this case, the contents of file given by the second parameter is
destroyed. This behaviour is dictated only by System V ptx
compatibility, because GNU Standards discourage output parameters not
introduced by an option.
Note that for any file named as the value of an option or as an input text file, a single dash - may be used, in which case standard input is assumed. However, it would not make sense to use this convention more than once per program invocation.
7.5.1 General options Options which affect general program behaviour. 7.5.2 Charset selection Underlying character set considerations. 7.5.3 Word selection and input processing Input fields, contexts, and keyword selection. 7.5.4 Output formatting Types of output format, and sizing the fields. 7.5.5 The GNU extensions to ptx
[ < ] | [ > ] | [ << ] | [ Up ] | [ >> ] | [Top] | [Contents] | [Index] | [ ? ] |
ptx
and switch to traditional mode.
[ < ] | [ > ] | [ << ] | [ Up ] | [ >> ] | [Top] | [Contents] | [Index] | [ ? ] |
As it is setup now, the program assumes that the input file is coded
using 8-bit ISO 8859-1 code, also known as Latin-1 character set,
unless if it is compiled for MS-DOS, in which case it uses the
character set of the IBM-PC. (GNU ptx
is not known to work on
smaller MS-DOS machines anymore.) Compared to 7-bit ASCII, the set of
characters which are letters is then different, this fact alters the
behaviour of regular expression matching. Thus, the default regular
expression for a keyword allows foreign or diacriticized letters.
Keyword sorting, however, is still crude; it obeys the underlying
character set ordering quite blindly.
[ < ] | [ > ] | [ << ] | [ Up ] | [ >> ] | [Top] | [Contents] | [Index] | [ ? ] |
This option provides an alternative (to `-W') method of describing which characters make up words. It introduces the name of a file which contains a list of characters which cannot be part of one word, this file is called the Break file. Any character which is not part of the Break file is a word constituent. If both options `-b' and `-W' are specified, then `-W' has precedence and `-b' is ignored.
When GNU extensions are enabled, the only way to avoid newline as a break character is to write all the break characters in the file with no newline at all, not even at the end of the file. When GNU extensions are disabled, spaces, tabs and newlines are always considered as break characters even if not included in the Break file.
The file associated with this option contains a list of words which will never be taken as keywords in concordance output. It is called the Ignore file. The file contains exactly one word in each line; the end of line separation of words is not subject to the value of the `-S' option.
There is a default Ignore file used by ptx
when this option is
not specified, usually found in `/usr/local/lib/eign' if this has
not been changed at installation time. If you want to deactivate the
default Ignore file, specify /dev/null
instead.
The file associated with this option contains a list of words which will be retained in concordance output, any word not mentioned in this file is ignored. The file is called the Only file. The file contains exactly one word in each line; the end of line separation of words is not subject to the value of the `-S' option.
There is no default for the Only file. In the case there are both an Only file and an Ignore file, a word will be subject to be a keyword only if it is given in the Only file and not given in the Ignore file.
On each input line, the leading sequence of non white characters will be taken to be a reference that has the purpose of identifying this input line on the produced permuted index. For more information about reference production, see See section 7.5.4 Output formatting. Using this option changes the default value for option `-S'.
Using this option, the program does not try very hard to remove references from contexts in output, but it succeeds in doing so when the context ends exactly at the newline. If option `-r' is used with `-S' default value, or when GNU extensions are disabled, this condition is always met and references are completely excluded from the output contexts.
This option selects which regular expression will describe the end of a line or the end of a sentence. In fact, there is other distinction between end of lines or end of sentences than the effect of this regular expression, and input line boundaries have no special significance outside this option. By default, when GNU extensions are enabled and if `-r' option is not used, end of sentences are used. In this case, the precise regex is imported from GNU emacs:
[.?!][]\"')}]*\\($\\|\t\\| \\)[ \t\n]* |
Whenever GNU extensions are disabled or if `-r' option is used, end of lines are used; in this case, the default regexp is just:
\n |
Using an empty regexp is equivalent to completely disabling end of line or end of sentence recognition. In this case, the whole file is considered to be a single big line or sentence. The user might want to disallow all truncation flag generation as well, through option `-F ""'. See section `Syntax of Regular Expressions' in The GNU Emacs Manual.
When the keywords happen to be near the beginning of the input line or sentence, this often creates an unused area at the beginning of the output context line; when the keywords happen to be near the end of the input line or sentence, this often creates an unused area at the end of the output context line. The program tries to fill those unused areas by wrapping around context in them; the tail of the input line or sentence is used to fill the unused area on the left of the output line; the head of the input line or sentence is used to fill the unused area on the right of the output line.
As a matter of convenience to the user, many usual backslashed escape
sequences, as found in the C language, are recognized and converted to
the corresponding characters by ptx
itself.
This option selects which regular expression will describe each keyword. By default, if GNU extensions are enabled, a word is a sequence of letters; the regexp used is `\w+'. When GNU extensions are disabled, a word is by default anything which ends with a space, a tab or a newline; the regexp used is `[^ \t\n]+'.
An empty regexp is equivalent to not using this option, letting the default dive in. See section `Syntax of Regular Expressions' in The GNU Emacs Manual.
As a matter of convenience to the user, many usual backslashed escape
sequences, as found in the C language, are recognized and converted to
the corresponding characters by ptx
itself.
[ < ] | [ > ] | [ << ] | [ Up ] | [ >> ] | [Top] | [Contents] | [Index] | [ ? ] |
Output format is mainly controlled by `-O' and `-T' options,
described in the table below. When neither `-O' nor `-T' is
selected, and if GNU extensions are enabled, the program choose an
output format suited for a dumb terminal. Each keyword occurrence is
output to the center of one line, surrounded by its left and right
contexts. Each field is properly justified, so the concordance output
could readily be observed. As a special feature, if automatic
references are selected by option `-A' and are output before the
left context, that is, if option `-R' is not selected, then
a colon is added after the reference; this nicely interfaces with GNU
Emacs next-error
processing. In this default output format, each
white space character, like newline and tab, is merely changed to
exactly one space, with no special attempt to compress consecutive
spaces. This might change in the future. Except for those white space
characters, every other character of the underlying set of 256
characters is transmitted verbatim.
Output format is further controlled by the following options.
Select the size of the minimum white gap between the fields on the output line.
Select the output maximum width of each final line. If references are used, they are included or excluded from the output maximum width depending on the value of option `-R'. If this option is not selected, that is, when references are output before the left context, the output maximum width takes into account the maximum length of all references. If this options is selected, that is, when references are output after the right context, the output maximum width does not take into account the space taken by references, nor the gap that precedes them.
Select automatic references. Each input line will have an automatic reference made up of the file name and the line ordinal, with a single colon between them. However, the file name will be empty when standard input is being read. If both `-A' and `-r' are selected, then the input reference is still read and skipped, but the automatic reference is used at output time, overriding the input reference.
In default output format, when option `-R' is not used, any reference produced by the effect of options `-r' or `-A' are given to the far right of output lines, after the right context. In default output format, when option `-R' is specified, references are rather given to the beginning of each output line, before the left context. For any other output format, option `-R' is almost ignored, except for the fact that the width of references is not taken into account in total output width given by `-w' whenever `-R' is selected.
This option is automatically selected whenever GNU extensions are disabled.
This option will request that any truncation in the output be reported using the string string. Most output fields theoretically extend towards the beginning or the end of the current line, or current sentence, as selected with option `-S'. But there is a maximum allowed output line width, changeable through option `-w', which is further divided into space for various output fields. When a field has to be truncated because cannot extend until the beginning or the end of the current line to fit in the, then a truncation occurs. By default, the string used is a single slash, as in `-F /'.
string may have more than one character, as in `-F ...'. Also, in the particular case string is empty (`-F ""'), truncation flagging is disabled, and no truncation marks are appended in this case.
As a matter of convenience to the user, many usual backslashed escape
sequences, as found in the C language, are recognized and converted to
the corresponding characters by ptx
itself.
Select another string to be used instead of `xx', while
generating output suitable for nroff
, troff
or TeX.
Choose an output format suitable for nroff
or troff
processing. Each output line will look like:
.xx "tail" "before" "keyword_and_after" "head" "ref" |
so it will be possible to write an `.xx' roff macro to take care of the output typesetting. This is the default output format when GNU extensions are disabled. Option `-M' might be used to change `xx' to another macro name.
In this output format, each non-graphical character, like newline and
tab, is merely changed to exactly one space, with no special attempt to
compress consecutive spaces. Each quote character: " is doubled
so it will be correctly processed by nroff
or troff
.
Choose an output format suitable for TeX processing. Each output line will look like:
\xx {tail}{before}{keyword}{after}{head}{ref} |
so it will be possible to write a \xx
definition to take care of
the output typesetting. Note that when references are not being
produced, that is, neither option `-A' nor option `-r' is
selected, the last parameter of each \xx
call is inhibited.
Option `-M' might be used to change `xx' to another macro
name.
In this output format, some special characters, like $, %,
&, # and _ are automatically protected with a
backslash. Curly brackets {, } are also protected with a
backslash, but also enclosed in a pair of dollar signs to force
mathematical mode. The backslash itself produces the sequence
\backslash{}
. Circumflex and tilde diacritics produce the
sequence ^\{ }
and ~\{ }
respectively. Other
diacriticized characters of the underlying character set produce an
appropriate TeX sequence as far as possible. The other non-graphical
characters, like newline and tab, and all others characters which are
not part of ASCII, are merely changed to exactly one space, with no
special attempt to compress consecutive spaces. Let me know how to
improve this special character processing for TeX.
[ < ] | [ > ] | [ << ] | [ Up ] | [ >> ] | [Top] | [Contents] | [Index] | [ ? ] |
ptx
This version of ptx
contains a few features which do not exist in
System V ptx
. These extra features are suppressed by using the
`-G' command line option, unless overridden by other command line
options. Some GNU extensions cannot be recovered by overriding, so the
simple rule is to avoid `-G' if you care about GNU extensions.
Here are the differences between this program and System V ptx
.
ptx
reads only one file and produce the result on standard output
or, if a second file parameter is given on the command, to that
file.
Having output parameters not introduced by options is a quite dangerous
practice which GNU avoids as far as possible. So, for using ptx
portably between GNU and System V, you should pay attention to always
use it with a single input file, and always expect the result on
standard output. You might also want to automatically configure in a
`-G' option to ptx
calls in products using ptx
, if
the configurator finds that the installed ptx
accepts `-G'.
ptx
are options `-b',
`-f', `-g', `-i', `-o', `-r', `-t' and
`-w'. All other options are GNU extensions and are not repeated in
this enumeration. Moreover, some options have a slightly different
meaning when GNU extensions are enabled, as explained below.
troff
or
nroff
. It is rather formatted for a dumb terminal. troff
or nroff
output may still be selected through option `-O'.
ptx
does not accept 8-bit characters, a few
control characters are rejected, and the tilde ~ is condemned.
ptx
processes only
the first 200 characters in each line.
ptx
,
but still, there are some slight disposition glitches this program does
not completely reproduce.
ptx
.
[ << ] | [ >> ] | [Top] | [Contents] | [Index] | [ ? ] |