Mastering UNIX Meta Characters: Tips and Techniques
Learn useful UNIX meta characters, how to turn them off, display lines, and explore essential Unix commands like wc, cmp, sort, uniq, compress, cut, find, with examples.
Mastering UNIX Meta Characters: Tips and Techniques
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Presentation Transcript
Meta Characters • Special Characters with Special Meaning • Used to Save Time • / \ “ ` * ; ? { } ( ) [ ] ~ ! $ < > | & # • # Comment Line • Turning Off Meta Characters • Display a Line of **** • echo *** • Doesn’t Work!
Meta Characters • Turning Off Meta Characters • \ • Turns Off One Meta Character $ echo \*\*\* ***
Meta Characters • Turning Off Meta Characters • ‘ ‘ • Turn off all Meta Characters between the ‘ ‘ $ echo ‘***’ ***
Meta Characters • Turning Off Meta Characters • “ “ • Turn off Meta Characters between the “ “ • $ \ ` remainactive $ echo “My home is $HOME” My home is /home/rdefe
Meta Characters • Turning Off Meta Characters with “ “ • $ \ ` remainactive $ echo -e “My home is $HOME\nNext Line” My home is /home/rdefe Next Line $ \n New Line \t Tab
Meta Characters • Turning Off Meta Characters • “ “ • Turn off Meta Characters between the “ “ • $ \ ` remainactive $ echo “Today is `date`” Today is Mon Jan 22 22:04:46 EST 1996
Unix Commands • wc [-lwc] File1 File2 … FileN • Word Count • -lDisplay Number of Lines • -wDisplay Number of Words • -cDisplay Number of Characters $ wc mbox 59 279 1473 mbox $ wc mbox ls.file 59 279 1473 mbox 1 1 12 ls.file 60 280 1485 total
Unix Commands • cmp File1 File2 • Compare Two Files (binary or text) $cmp s1 mbox s1 mbox differ: char 1, line 1 $ cmp p1 p2 $
Unix Commands • sort [-fnr]File1 File2 … FileN • Sort the Contents of a File • -fIgnore Case • -nSort Numbers Based on Value • -rReverse Order $ cat words sand box zoo xray sam jones $ sort words box jones sam sand xray zoo
Unix Commands • uniq [-d]File1 File2 … FileN • Read a Sorted File Reject or Report Duplicates • -dDisplay Duplicates $ cat stuff dos mac mvs mvs unix unix windows95 $ uniq stuff dos mac mvs unix windows95 $ uniq -d stuff mvs unix
Unix Commands • compress File1 File2 … FileN • uncompress File1 File2 … FileN • Used to compress Large Files $ ls -s datafile 297 datafile $ compress datafile $ ls -s datafile* 177 datafile.Z $ uncompress datafile $ ls -s datafile 297 datafile
Unix Commands • cut -c[col number] FileName • Cut columns and display to screen $ cat names Jones John Smith Rober Doe John $ cut -c1-3 names Jon Smi Doe $ cut -c1-3,11-13 names JonJoh SmiRob DoeJoh
Unix Commands • find LocationCriteriaAction • Locate Files Based on a Search Criteria $find /home -name mbox -print /home/mbox /home/rdefe/mbox /home/ssmith/mbox $ $find /home -name “mbox*” -print $
Unix Commands • find LocationCriteriaAction • Specify Multiple Search Locations $find /home /usr -name mbox -print /home/mbox /home/rdefe/mbox /home/ssmith/mbox /usr/mbox /usr/tmp/mbox $
Unix Commands • find LocationCriteriaAction • -user [login] • -group [GroupName] $find /home -user rdefe -print /home/rdefe/mbox /home/rdefe/doc $ $find /home -group unix -print /home/rdefe/mbox /home/rdefe/doc /home/jsmith/p1 $
$find /home -mtime +7 -print Files modified greater than 7 days ago $find /home -mtime -7 -print Files modified less than 7 days ago Unix Commands • find LocationCriteriaAction • -mtime [+|-] Days • -links [+|-] Number Files modified exactly 7 days ago $find /home -mtime 7 -print
Unix Commands • find LocationCriteriaAction • -inum [InodeNumber] • -type [f|d] Find file with inode number 10203 $find /home -inum 10203 -print $find /home -type d -print Find all directories in /home
Unix Commands • find LocationCriteriaAction • -print Display File Location • -exec UnixCmds Execute Unix Command(s) • -ok UnixCmds Interactive Unix Command(s) $find /home -user rdefe -exec pr {} \; $find /home -user rdefe -ok pr {} \; /home/rdefe/mbox? Prompt for Each File
Implied “and” $find /home -user rdefe -links 2 -print $find /home -user rdefe -o -links 2 -print “or” Unix Commands • find Examples $find /home \( -user rdefe -o -user jdoe \) -links 2 -print