07-01-2011
Command comparisons
Hi guys,
Im trying to figure out what is the difference between using a | and the command xargs ... examples of usage:
1) ls * | wc -w => this gives you the number of files in the current directory including all subdirectories
2) find . “*.log” | xargs grep ERROR => this gives you all the occurrences of ERROR in all .log files in the current directory and all subdirectories
PLUS! what is the difference of the above commands to this one below and why should I use one instead of the other:
find . “*.log” -exec grep ERROR ‘{}' \;
Any help will be very much appreciated.
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LEARN ABOUT LINUX
dpkg-name
dpkg-name(1) dpkg utilities dpkg-name(1)
NAME
dpkg-name - rename Debian packages to full package names
SYNOPSIS
dpkg-name [options] [--] files
DESCRIPTION
This manual page documents the dpkg-name program which provides an easy way to rename Debian packages into their full package names. A full
package name consists of <package>_<version>_<architecture>.<package_type> as specified in the control file of the package. The <version>
part of the filename consists of the upstream version information optionally followed by a hyphen and the revision information. The <pack-
age_type> part comes from that field if present or fallbacks to deb.
OPTIONS
-a, --no-architecture
The destination filename will not have the architecture information.
-k, --symlink
Create a symlink, instead of moving.
-o, --overwrite
Existing files will be overwritten if they have the same name as the destination filename.
-s, --subdir [dir]
Files will be moved into a subdirectory. If the directory given as argument exists the files will be moved into that directory oth-
erwise the name of the target directory is extracted from the section field in the control part of the package. The target directory
will be `unstable/binary-<architecture>/<section>'. If the section is not found in the control, then `no-section' is assumed, and in
this case, as well as for sections `non-free' and `contrib' the target directory is `<section>/binary-<architecture>'. The section
field isn't required so a lot of packages will find their way to the `no-section' area. Use this option with care, it's messy.
-c, --create-dir
This option can used together with the -s option. If a target directory isn't found it will be created automatically. Use this
option with care.
-h, --help
Show the usage message and exit.
-v, --version
Show the version and exit.
EXAMPLES
dpkg-name bar-foo.deb
The file `bar-foo.deb' will be renamed to bar-foo_1.0-2_i386.deb or something similar (depending on whatever information is in the
control part of `bar-foo.deb').
find /root/debian/ -name '*.deb' | xargs -n 1 dpkg-name -a
All files with the extension `deb' in the directory /root/debian and its subdirectory's will be renamed by dpkg-name if required
into names with no architecture information.
find -name '*.deb' | xargs -n 1 dpkg-name -a -o -s -c
Don't do this. Your archive will be messed up completely because a lot of packages don't come with section information. Don't do
this.
dpkg --build debian-tmp && dpkg-name -o -s .. debian-tmp.deb
This can be used when building new packages.
BUGS
Some packages don't follow the name structure <package>_<version>_<architecture>.deb. Packages renamed by dpkg-name will follow this struc-
ture. Generally this will have no impact on how packages are installed by dselect(1)/ dpkg(1), but other installation tools might depend on
this naming structure.
SEE ALSO
deb(5), deb-control(5), dpkg(1), dpkg-deb(1), find(1), xargs(1).
AUTHOR
Copyright (C) 1995,1996 Erick Branderhorst
This is free software; see the GNU General Public Licence version 2 or later for copying conditions. There is NO WARRANTY.
Debian Project 2008-08-18 dpkg-name(1)