UNIX/LINUX in 25 commands (or less)

  DIRECTORY

  cd                change directory
  cd ..             drop one level
  cd ~/dirname      back to root directory, then to dirname
  cd dir1/dir2      change directory at higher level

  pwd               print working directory (where am I?)

  ls dirname        list files in dirname
              Options:
        -l      show directory files with long format
        -a      include files beginning with .
        -d      just name of directory not contents (with *)
        -t      list in chronological order
              Wildcards:
         ? single character
         * anything

  mkdir dirname     make (create) a directory
  rmdir dirname     remove (delete) a directory


  FILES             can name file from current directory
                     as dir1/dir2/filename

  cp file1 file2    copies file1 to file2 (automatic overwrite)
  cp file1 dir      copies file1 to directory dir (same filename)

  mv file1 file2    renames -- file1 has new name 'file2'
  mv file dirname   moves file from current directory to dirname

  rm file           removes (erases) file
  rm -f file        remove -- and don't ask for confirmation

  dos2unix filename converts dos(Windows) file to unix
  
  ~/dir1/dir2/file  names file from root (~) directory
 

  CONTENTS AND MANIPULATION

  head file         print the first 10 lines of file
  head -23 file     print the first 23 lines
  
  tail file         print the last 10 lines
  tail -3 file      print the last 3 lines
  
  more file         look at file a screenful at a time
  less file         more sophisticated

  wc file           gives count of lines, words, and characters

  grep 'text' files finds 'text' in files
  grep '%let' *.sas
  egrep regexp file find lines with regular expression regexp

  cmp file1 file2   compares file1 and file2 (0 if same, 1 not same)
  diff file1 file2  compares files -- gives more info than cmp

  cat file          lists contents of file
  cat file1 file2 > both
                    concatenates file1 and file2 and puts in file both

  paste file1 file2 concatenates file1 and file2 in side-by-side manner

  cut -cstart-stop file1     prints cols start to stop of file file1
  cut -c11-72 f1 > file2     writes cols 11-72 of file1 into file2 
  cut -c1,5-9 file1 > file2  writes cols 1 and 5-9 of file1 into file2
  cut -f1,3 -d, file1       writes items 1 and 3 of file1 using ',' 
                             as delimeter (one char only)
  cut -f3 -d, -s file1      writes item 3 of file1 with comma delimiter 
                             and no lines without comma

  sort filename          sorts filename (by ascii character order)
  sort -r filename       sorts in reverse order
             Other options:
             -b     ignore leading blanks
             -g     general-numeric sort  (3 vs 12)

  uniq filename          deletes common records
  uniq -c filename       gives count of common records (as proc freq)

  
  SED SIMPLE EDITOR COMMANDS

  sed 's/pat/repl/' file    change 'pat' to 'repl' in file
  sed 's/pat/repl/3' file   change just 3rd occurence
  sed 's/pat/repl/g' file   change all occurences
  sed 'y/abc/def/' file     substitute char for char (e.g. abc for bca)


  PIPING AND DIRECTION

  command > file1   direct output of command to file1
  command >> file1  as above, but append to previous contents
  command < file2   use file2 as input to command
  command < file2 > file1     combine above 
  command1 | command2         pipe output from command1 to command2


  PRINTING 
 
  lpr file          print file
  lpq               print queue status

  a2ps              prints in two column format (80 cols wide)
  

  HELP              get info

  man command       display reference manual for command
  whatis command    display one line description of command


  JOB CONTROL

  command &         run command in background

  kill -9 num       kills process num

  ps                program status (what's running)
        

  J F Monahan, Nov 2008, 2009
 update of handout by Tim Arnold dated 1990