Frequently used UNIX commands

Managing Directories

 pwd		  show the current working directory
 cd xyz	   	  change working directory to xyz
 mkdir xyz	  create directory named xyz
 rmdir xyz	  remove/delete directory named xyz		

Directory Identifiers

 ~(tilde)         your home directory
 .(dot)           the current working directory
 ..               the parent directory (one level up)
 /                root directory

Managing Files

 ls		  list files in the working directory
 ls file1	  list file file1 if it exists in the working directory
 ls dir1 	  list contents of the directory dir1
 ls -l		  list directory contents with addtional information
		  (long listing)
 ls -a		  list all files including hidden ones (.* files)
 cat file1	  display contents of file1
 more file1	  display contents of file1, one page at a time
 head -n file1    display first n lines (default=10) of file1
 tail -n file1    display last  n lines (default=10) of file1
 rm file1 	  remove/delete file1
 rm -i file1      remove/delete file1 but inquire for confirmation	
 cp file1 file2	  copy file1 to file2
 cp file1 dir1    copy file1 into directory dir1
 mv file1 file2   move file1 to file2 (i.e., rename file1 to file2)
 mv file1 dir1    move file1 into directory dir1
 diff file1 file2 display lines which are different in file1 and file2

For more descriptive help on searching, sorting etc., go to 
File Manipulation Utilities.

Managing Jobs

 ctrl-c           kill current job
 ctrl-z           suspend current job
 bg		  run suspended job in background
 fg	          bring suspended/background job to foreground
 ps		  list processes by their process identifier (PID)
 kill PID	  kill process with process identifier PID			
 jobs		  list your jobs by job number

On-line help

 man command	  display manual entry for command
 man -k keyword	  list manual pages that pertain to keyword
 insight 	  on-line help on SGI (X version)
 learn		  on-line tutorial on IBM

System Information

 who               list users logged onto the system
 whoami            displays your logon ID (username)
 df                display number of free blcoks on disk
 du                display disk usage

Utility Programs

 wc file1           displays the number of lines, words and characters
                    in file1      
 sort file1         sort contents of file, send results to 
                    standard output
 grep pattern file1 look for pattern in file1, send
                    results to standard output
 tar file1          write to or retrieve file1 from an archival
                    storage medium (e.g., tape)
 compress file1     compresses file1 and writes file1.Z
 uncompress file1.Z restores file1 from compressed format 
 uniq file1 file2   delete duplicate lines in file1 and 
                    write the new version of file1 into file2
 find path -name   \search the directory tree path
     file -print   /for file and display
 echo string        translate parameter string and display

Special Characters

 *                 match any character (wild card)
 &                 put job in background
 !                 repeat previous command
 ;                 Concatenate several commands on one line
 #                 start of a comment
 #!                first two characters of a shell script

I/O Redirection Commands (csh, tcsh)

 
 <                 redirect standard input (get input from)
 >                 redirect standard output (write output to)
 >&                redirect standard output and standard error
 >!                redirect standard output, overwrite file if it exists
 >!&               redirect standard output and error,  overwrite file if it exists 
 |                 send output from first command to input of second command (pipe)
 >>                append standard output
 >>&               append standard output and error
 

Links to other D0 pages