Fedora And Red Hat System Administration/Archives And Compression

Compressing Data gzip and gunzip Under Construction bzip2 and bunzip2 Under Construction tar - *NIX Archives Under Construction Creating a tar archive To create an uncompressed tar archive, the c and f options are provided (think 'c' for create and 'f' for filename): [user@station user]$ tar cf foo.tar file1 file2 file3 The first argument is the name of the archive, in this case foo.tar. Any following arguments are the files that are being archived (e.g. file1 file2 file3). Usually globbing is used to archive all files of a particular type (e.g. tar cf foo.tar *.cpp will archive all of the .cpp files in the current directory): To archive all files and subdirectories within a directory, the same options are provided, but the second argument is the . character which symbolizes the current working directory: [user@station user]$ tar cf foo.tar . To compress the contents of the archive one of the z, J, or j options are used. Each option corresponds to a different compression algorithm, which in order are: gzip, xz, and bzip2. For example, to create a gzip compressed archive of the current directory the following would be run: [user@station user]$ tar cfz foo.tar.gz . Inspecting a tar archive Under Construction Extracting a tar archive Under Construction cpio - Flexible Archiving Tool In general, tar is the preferred method for creating archives, but in some cases a particular archive format may be desired and cpio provides a greater degree of control over how the archive is generated at the cost of greater complexity. Creating a cpio archive To create a cpio archive, the -o option is provided (think 'o' for "The archive is being written out"). cpio expects a list of files to be provided to its standard input. The list of files is usually provided by piping results from the find command. The -H option can be used to specify the archive format, see the man page for more information. [user@station user]$ find playground/ playground/ playground/AUTHORS playground/ChangeLog playground/COPYING playground/foo.txt playground/newfile [user@station user]$ find playground/ | cpio -o >archive 1212 blocks [user@station user]$ ls -l archive -rw-rw-r-- 1 user user 620544 Jan 5 08:49 archive [user@station user]$ file archive archive: cpio archive Listing contents of an archive with cpio To view the contents of an archive the -i option is provided to tell cpio to expect the archive data on its standard input. The -t option is also used then to tell cpio to not extract, but rather simply list the contents of the archive. [user@station user]$ cpio -it <archive playground/ playground/AUTHORS playground/ChangeLog playground/COPYING playground/foo.txt playground/newfile 1212 blocks Extracting an archive with cpio The -i option is used with a combination of options to tell it how to extract. Common choices include -d to tell cpio to create directories as needed. -m to reset file modification times. -R to change file ownership. [user@station user]$ cd /tmp [user@station tmp]$ cpio -idm <archive 1212 blocks [user@station tmp]$ find playground/ playground/ playground/AUTHORS playground/ChangeLog playground/COPYING playground/foo.txt playground/newfile zip - PKZIP style archives Creating a zip archive [user@station user]$ zip -r playground.zip playground adding: playground/ (stored 0%) adding: playground/AUTHORS (deflated 63%) adding: playground/COPYING (deflated 62%) adding: playground/foo.txt (stored 0%) adding: playground/newfile (deflated 39%) adding: playground/ChangeLog (deflated 70%) [user@station user]$ ls -l playground.zip -rw-r--r-- 1 user user 71607 Jan 11 14:33 playground.zip Listing contents of a zip archive [user@station user]$ unzip -l playground.zip Archive: playground.zip Length Date Time Name -------- ---- ---- ---- 0 01-11-05 14:33 playground/ 2110 01-11-05 14:32 playground/AUTHORS 17992 01-11-05 14:33 playground/COPYING 22 01-11-05 14:33 playground/foo.txt 44 01-11-05 14:33 playground/newfile 212169 01-11-05 14:32 playground/ChangeLog -------- ------- 232337 6 files Unpacking a zip archive [user@station user]$ rm -rf playground [user@station user]$ unzip playground.zip Archive: playground.zip creating: playground/ inflating: playground/AUTHORS inflating: playground/COPYING extracting: playground/foo.txt inflating: playground/newfile inflating: playground/ChangeLog dump - Filesystem Level Backup Under Construction