NAME
grep-dctrl, grep-status, grep-available, grep-aptavail, grep-debtags -
grep Debian control files
SYNOPSIS
command --copying|-C | --help|-h | --version|-V
command [options] predicate [ file... ]
where command is one of grep-dctrl, grep-status, grep-available,
grep-aptavail and grep-debtags.
DESCRIPTION
The grep-dctrl program can answer such questions as What is the Debian
package foo?, Which version of the Debian package bar is now current?,
Which Debian packages does John Doe maintain?, Which Debian packages
are somehow related to the Scheme programming language?, and with some
help, Who maintain the essential packages of a Debian system?, given a
useful input file.
The programs grep-available, grep-status, grep-aptavail and
grep-debtags are aliases of (actually, symbolic links to) grep-dctrl.
In the shipped configuration, these aliases use as their default input
the dpkg(8) available and status files, the apt-cache dumpavail output
and the debtags dumpavail output, respectively.
grep-dctrl is a specialised grep program that is meant for processing
any file which has the general format of a Debian package control file,
as described in the Debian Packaging Manual. These include the dpkg
available file, the dpkg status file, and the Packages files on a
distribution medium (such as a Debian CD-ROM or an FTP site carrying
Debian).
You must give a filter expression on the command line. The filter
defines which kind of paragraphs (aka package records) are output. A
simple filter is a search pattern along with any options that modify
it. Possible modifiers are --eregex, --field, --ignore-case, --regex
and --exact-match, along with their single-letter equivalents. By
default, the search is a case-sensitive fixed substring match on each
paragraph (in other words, package record) in the input. With suitable
modifiers, this can be changed: the search can be case-insensitive and
the pattern can be seen as an extended POSIX regular expression.
Filters can be combined to form more complex filters using the
connectives --and, --or and --not. Parentheses (which usually need to
be escaped for the shell) can be used for grouping.
By default, the full matching paragraphs are printed on the standard
output; specific fields can be selected for output with the -s option.
After the filter expression comes zero or more file names. If no file
names are specified, the file name is searched in configuration files.
The input file from the first program name - input file association
with the correct program name is used. The program names are matched
with the base form of the name of the current program (the 0’th command
line argument, if you will). The file name "-" is taken to mean the
standard input stream. The files are searched in order but separately;
they are not concatenated together. In other words, the end of a file
always implies the end of the current paragraph.
There is one exception to the above: if the program name is grep-dctrl,
the default input source is always standard input; this cannot be
overridden by the configuration file.
OPTIONS
Specifying the search pattern
--pattern=PATTERN
Specify a pattern to be searched. This switch is not generally
needed, as the pattern can be given by itself. However, patterns
that start with a dash must be given using this switch, so that
they wouldn’t be mistaken for switches.
Modifiers of simple filters
-F FIELD,FIELD,...; --field=FIELD,FIELD,...
Restrict pattern matching to the FIELDs given. Multiple field
names in one -F option and multiple -F options in one simple
filter are allowed. The search named by the filter will be
performed among all the fields named, and as soon as any one of
them matches, the whole simple filter is considered matching.
A FIELD specification can contain a colon. In such a case, the part up
to the colon is taken as the name of the field to be searched in, and
the part after the colon is taken as the name of the field whose
content is to be used if the field to search in is empty.
-P Shorthand for "-FPackage".
-S Shorthand for "-FSource:Package".
-e, --eregex
Regard the pattern of the current simple filter as an extended
POSIX regular expression
-r, --regex
The pattern of the current simple filter is a standard POSIX
regular expression.
-i, --ignore-case
Ignore case when looking for a match in the current simple
filter.
-X, --exact-match
Do an exact match (as opposed to a substring match) in the
current simple filter.
-w, --whole-pkg
Do an extended regular expression match on whole package names,
assuming the syntax of inter-package relationship fields such as
Depends, Recommends, ... When this flag is given you should not
worry about sub-package names such as "libpcre3" also matching
"libpcre3-dev". This flag implies (and is incompatible with) -e.
--eq Do an equality comparison under the Debian version number
system. If the pattern or the field to be searched in is not a
valid Debian version number, the paragraph is regarded as not
matching. As a special case, this is capable of comparing
simple nonnegative integers for equality.
--lt Do an strictly-less-than comparison under the Debian version
number system. If the pattern or the field to be searched in is
not a valid Debian version number, the paragraph is regarded as
not matching. As a special case, this is capable of comparing
simple nonnegative integers.
--le Do an less-than-or-equal comparison under the Debian version
number system. If the pattern or the field to be searched in is
not a valid Debian version number, the paragraph is regarded as
not matching. As a special case, this is capable of comparing
simple nonnegative integers.
--gt Do an strictly-greater-than comparison under the Debian version
number system. If the pattern or the field to be searched in is
not a valid Debian version number, the paragraph is regarded as
not matching. As a special case, this is capable of comparing
simple nonnegative integers.
--ge Do an greater-than-or-equal comparison under the Debian version
number system. If the pattern or the field to be searched in is
not a valid Debian version number, the paragraph is regarded as
not matching. As a special case, this is capable of comparing
simple nonnegative integers.
Combining filters
-!, --not, !
Match if the following filter does not match.
-o, --or
Match if either one or both of the preceding and following
filters matches.
-a, --and
Match if both the preceding and the following filter match.
( ... )
Parentheses can be used for grouping. Note that they need to be
escaped for most shells.
Output format modifiers
-s FIELD,FIELD,...; --show-field=FIELD,FIELD,...
Show only the body of these fields from the matching paragraphs.
The field names must not include any colons or commas. Commas
are used to delimit field names in the argument to this option.
The fields are shown in the order given here. See also the
option -I.
-I; --invert-show
Invert the meaning of option -s: show only the fields that have
not been named using a -s option. As an artefact of the
implementation, the order of the fields in the original
paragraph is not preserved.
A FIELD specification can contain a colon. In such a case, the part up
to the colon is taken as the name of the field to be shown, and the
part after the colon is taken as the name of the field whose content is
to be used if the field to be shown is empty.
-d Show only the first line of the Description field from the
matching paragraphs. If no "-s" option is specified, this
option also effects "-s Description"; if there is a "-s" option
but it does not include the Description field name, one is
appended to the option. Thus the Description field’s location
in the output is determined by the "-s" option, if any, the last
field being the default.
-n, --no-field-names
Suppress field names when showing specified fields, only their
bodies are shown. Each field is printed in its original form
without the field name, the colon after it and any whitespace
preceding the start of the body.
-v, --invert-match
Instead of showing all the paragraphs that match, show those
paragraphs that do not match.
-c, --count
Instead of showing the paragraphs that match (or, with -v, that
don’t match), show the count of those paragraphs.
-q, --quiet, --silent
Output nothing to the standard output stream. Instead, exit
immediately after finding the first match.
Miscellaneous
--ignore-parse-errors
Ignore errors in parsing input. A paragraph which cannot be
parsed is ignored in its entirety, and the next paragraph is
assumed to start after the first newline since the location of
the error.
--config-file=FNAME
Use FNAME as the config file instead of the defaults.
--debug-optparse
Show how the current command line has been parsed.
-l LEVEL, --errorlevel=LEVEL
Set debugging level to LEVEL. LEVEL is one of "fatal",
"important", "informational" and "debug", but the last may not
be available, depending on the compile-time options. These
categories are given here in order; every message that is
emitted when "fatal" is in effect, will be emitted in the
"important" error level, and so on. The default is "important".
-V, --version
Print out version information.
-C, --copying
Print out the copyright license. This produces much output; be
sure to redirect or pipe it somewhere (such as your favourite
pager).
-h, --help
Print out a help summary.
EXAMPLES
The following example queries assume that the default configuration is
in effect.
The almost simplest use of this program is to print out the status or
available record of a package. In this respect, grep-dctrl is like
dpkg -s or dpkg --print-avail. To print out the status record of the
package "mixal", do
% grep-status -PX mixal
and to get its available record, use
% grep-available -PX mixal
In fact, you can ask for the record of the "mixal" package from any
Debian control file. Say, you have the Debian 2.2 CD-ROM’s Packages
file in the current directory; now you can do a
% grep-dctrl -PX mixal Packages
But grep-dctrl can do more than just emulate dpkg. It can more-or-less
emulate apt-cache! That program has a search feature that searches
package descriptions. But we can do that too:
% grep-available -F Description foo
searches for the string "foo" case-sensitively in the descriptions of
all available packages. If you want case-insensitivity, use
% grep-available -F Description -i foo
Truth to be told, apt-cache searches package names, too. We can
separately search in the names; to do so, do
% grep-available -F Package foo
or
% grep-available -P foo
which is pretty much the same thing. We can also search in both
descriptions and names; if match is found in either, the package record
is printed:
% grep-available -P -F Description foo
or
% grep-available -F Package -F Description foo
This kind of search is the exactly same that apt-cache does.
Here’s one thing neither dpkg nor apt-cache do. Search for a string in
the whole status or available file (or any Debian control file, for
that matter) and print out all package records where we have a match.
Try
% grep-available dpkg
sometime and watch how thoroughly dpkg has infiltrated Debian.
All the above queries were based on simple substring searches. But
grep-dctrl can handle regular expressions in the search pattern. For
example, to see the status records of all packages with either "apt" or
"dpkg" in their names, use
% grep-status -P -e ’apt|dpkg’
Now that we have seen all these fine and dandy queries, you might begin
to wonder whether it is necessary to always see the whole paragraph.
You may be, for example, interest only in the dependency information of
the packages involved. Fine. To show the depends lines of all
packages maintained by me, do a
% grep-available -F Maintainer -s Depends ’ajk@debian.org’
If you want to see the packages’ names, too, use
% grep-available -F Maintainer -s Package,Depends \
’ajk@debian.org’
Note that there must be no spaces in the argument to the -s switch.
More complex queries are also possible. For example, to see the list
of packages maintained by me and depending on libc6, do
% grep-available -F Maintainer ’ajk@debian.org’ \
-a -F Depends libc6 -s Package,Depends
Remember that you can use other Unix filters to help you, too. Ever
wondered, who’s the most active Debian developer based on the number of
source packages being maintained? Easy. You just need to have a copy
of the most recent Sources file from any Debian mirror.
% grep-dctrl -n -s Maintainer ’’ Sources | sort |
uniq -c | sort -nr
This example shows a neat trick: if you want to selectively show only
some field of all packages, just supply an empty pattern.
The term "bogopackage" means the count of the packages that a Debian
developer maintains. To get the bogopackage count for the maintainer
of grep-dctrl, say
% grep-available -c -FMaintainer \
"‘grep-available -sMaintainer -n -PX grep-dctrl‘"
Sometimes it is useful to output the data of several fields on the same
line. For example, the following command outputs the list of installed
packages, sorted by their Installed-Size.
% grep-status -FStatus -sInstalled-Size,Package -n \
"install ok installed" | paste -sd " \n" | sort -n
Note that there should be exactly 2 spaces in the " \n" string.
These examples cover a lot of typical uses of this utility, but not all
possible uses. Use your imagination! The building blocks are there,
and if something’s missing, let me know.
DIAGNOSTICS
In the absence of errors, the exit code 0 is used if at least one match
was found, and the exit code 1 is used if no matches were found. If
there were errors, the exit code is 2, with one exception. If the -q,
--quiet or --silent options are used, the exit code 0 is used when a
match is found regardless of whether there have been non-fatal errors.
These messages are emitted in log levels "fatal" and "important".
Additional messages may be provided by the system libraries. This list
is out of date.
a pattern is mandatory
You must specify a pattern to be searched for.
a predicate is required
No predicate was specified, but one is required.
cannot find enough memory
More memory was needed than was available. This error may be
transient, that is, if you try again, all may go well.
cannot suppress field names when showing whole paragraphs
When you do not use the -s switch, grep-dctrl just passes the
matching paragraphs through, not touching them any way. This
means, for example, that you can only use -n when you use -s.
inconsistent atom modifiers
Conflicting atom modifiers were used; for example, perhaps both
-X and -e were specified for the same atom.
missing ’)’ in command line
There were more opening than closing parentheses in the given
predicate.
no such log level
The argument to -l was invalid.
predicate is too complex
The predicate’s complexity (the number of atoms and connectives)
exceed compile-time limits.
read failure or out of memory
There was a problem reading the configuration file. Maybe there
was a transput error; maybe memory was exhausted. This error
may be transient, that is, if you try again, all may go well.
syntax error in command line
There is a problem in the command line. Look, and you shall
find it.
syntax error: need a executable name
There is a problem in the configuration file. Look, and you
shall find it.
syntax error: need an input file name
There is a problem in the configuration file. Look, and you
shall find it.
too many file names
The number of file names specified in the command line exceeded
a compile-time limit.
too many output fields
The argument to -s had too many field names in it. This number
is limited to 256.
unexpected ’)’ in command line
There was no opening parenthesis that would match some closing
parenthesis in the command line.
unexpected end of file
The input file is broken: it ends before it should.
unexpected end of line
The input file is broken: a line ends before it should.
Unexpected atom in command line. Did you forget to use a connective?
There was an atom on the command line where there should not be
any. The most likely reason is that an atom modifier option
(such as -F) follows directly after a closing parenthesis.
Adding a connective (--and, --or) between the parenthesis and
the option is often the correct solution.
COMPATIBILITY
If you use grep-dctrl in a Debian package, you should depend on the
grep-dctrl package and heed the following compatibility notes:
Always call only the grep-dctrl executable.
Although the grep-status and grep-available symlinks are
installed by default, this may change in the future. Those
symlinks are meant for manual and not scripted use.
Always specify an explicit file name
Don’t rely on the implicit file name feature. The system
administrator may have changed the default file name. You
should always specify the "-" file, too.
Not all features have been with us in every version
Check if any of the features you use is mentioned in the
changelog. Use a versioned dependency on grep-dctrl, if it is
necessary.
FILES
/etc/grep-dctrl.rc
See the next file.
~/.grep-dctrlrc
These files are the default configuration files for grep-dctrl.
The format is line-based, with ‘#’ introducing a comment that
lasts to the end of the line. Each line defines one association
between a program name and a default input file. These two
things are listed in the line in order, separated by whitespace.
Empty lines are ignored.
If the default input file name starts with two at (@) signs, one
of them is ignored. This allows specifying a file name that
starts with an at sign. If it starts with the string "@exec",
the rest of the name is interpreted as a command name that is
fed to /bin/sh -c, and the standard output stream is used as the
default input.
/var/lib/dpkg/available
The default input file of grep-available when the shipped
configuration is in effect.
/var/lib/dpkg/status
The default input file of grep-status when the shipped
configuration is in effect.
AUTHOR
The program and this manual page were written by Antti-Juhani Kaijanaho
<gaia@iki.fi>. Bill Allombert <ballombe@debian.org> provided one of
the examples in the manual page.
SEE ALSO
Ian Jackson et al.: Debian Packaging Manual. Published as the Debian
package packaging-manual. Also available in the Debian website. The
Debian project, 2003.
ara(1), apt-cache(1), dpkg(8), dpkg-awk(1), sgrep(1)