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Archive Utilities

Archive Utilities. Learning Objectives: To introduce different archive utilities for file compression with their usage To compare & summarized different archive utilities. Archive Utilities. Table of Content Compress gzip compression Zip compression (PC Compatible)

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Archive Utilities

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  1. Archive Utilities Learning Objectives: To introduce different archive utilities for file compression with their usage To compare & summarized different archive utilities

  2. Archive Utilities Table of Content • Compress • gzip compression • Zip compression (PC Compatible) • Zip (PC pkzip Compatible) • Unzip (PC pkunzip Compatible) • tar archive • No compression • Selective restore • With Compression • Cpio ( selected reference ) • Summary

  3. Summary (*) Not available in all systems, may need to download, see www.gnu.org

  4. Compress / Uncompress • Compression single file and available on most systems • Compressed .z file smaller, file date preserved • Actually compression ratio depend on data (text file and database files usually larger) $ ls -l buyer* 22651778 Nov 16 18:45 buyer.dbf $ compress buyer.dbf $ ls -l buyer* 3603257 Nov 16 18:45 buyer.dbf.Z $ uncompress buyer.dbf.Z $ ls -l buyer* 22651778 Nov 16 18:45 buyer.dbf

  5. gzip Compression • Backward compatible with compress, better compression ratio • Available from GNU www.gnu.org • gunzip – un-compresses $ gzip –h gzip 0.7 (5 Jan 93) usage: gzip [-cdfhLrtvV19] [file ...] -c --stdout write on standard output, keep original files unchanged -d --decompress decompress -f --force force overwrite of output file and compress links -h --help give this help -L --license display software license -r --recurse recurse through directories -t --test test compressed file integrity -v --verbose verbose mode -V --version display version number -1 --fast compress faster -9 --best compress better file... files to (de)compress. If none given, use standard input.

  6. tar archive $ tar cvf /tmp/tar2.tar * a letter0 1K a secret/ 0K a secret/letter1 1K a secret/letter2 1K • Traditional archive utility – backup directory tree(s) $ tar cvf /tmp/tar1.tar . a ./ 0K a ./letter0 1K a ./secret/ 0K a ./secret/letter1 1K a ./secret/letter2 1K $ tar xvf /tmp/tar1.tar Restores the directory tree

  7. Disks Usage Statistics • df display free blocks and # of files in each file system $ df | head /proc (/proc ): 0 blocks 934 files / (/dev/dsk/c0t3d0s0 ): 226544 blocks 280996 files /dev/fd fd ): 0 blocks 0 files /var (/dev/dsk/c0t3d0s3 ): 1480320 blocks 252851 files /cache (/dev/dsk/c0t3d0s4 ): 308472 blocks 243243 files /home (/dev/dsk/c0t3d0s7 ): 1408858 blocks 284098 files /tmp (swap ): 2903968 blocks 10169 files /var/mail(mail:/mail ):14054672 blocks 1097254 files /var/spool/uucp (mail:/var/spool/uucp): 3450734 blocks 350809 files • du display disk usage statistics (in number of 512k blocks) $ du | head -5 282 ./zmodem 14 ./gzip-0.7/msdos 2 ./gzip-0.7/os2 662 ./gzip-0.7 3626 ./mail du shows disk usage of directories in 512k blocks

  8. User Groups (2) • View users of a group $ ypcat group | grep comp111 comp111:*:40000:kwchiu,john usage: groupmod [-g gid [-o]] [-n name] group • Renaming a group (super-user only) $ groupmod usage: groupmod [-g gid [-o]] [-n name] group $ groupmod -n cs111 comp111 • Deleting a group $ groupdel usage: groupdel group $ groupdel cs111

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