Extremely Useful UNIX/Linux Commands

Solution:

• man
  This program displays manual pages for most of the programs and some of the configurations on your server. You can even get info on the man program itself. You can use the -k option to search for a word in the manual page description. Each manual page has a category number. You only need to enter the category number when two manual pages in different sections have the same name.
  Examples:

  man man
  man ls
  man -k crontab
  man 1 crontab
  man 5 crontab
  
                                                     

  If man -kyields no results, run /usr/libexec/makewhatis.local to build the whatis data files.

• su
  Switch to a different user in order to have their access priveleges without telneting in again. When no username is provided, su will switch you to root (superuser). You will be prompted for the user's password unless you have superuser priveleges. Usually the - option should be used since it loads all the configuration files for the user.
  Examples:

  su
  su -
  su bob
  su - bob
  
                                                     

  
  
• ls
  List contents of the directory.
  
• pwd
  Print Working Directory. Display the name of the directory that you are currently in.
  
• cd
  Change Directory.
  
• mv
  Move a file or directory
  
• rm
  Remove file.
  
• rmdir
  Remove directory.
  
• chown
  Change the owner of a file or directory.
  
• chmod
  Change Mode. Change the access restrictions for a file or directory.
  
• du
  Display the disk usage for a directory and its subdirectories.
  
• df
  Display the free disk space information.
  
• ping
  Ping an IP address or domain name to see if that server is active.
  
• host
  Look up a DNS entry for an IP address or domain name.
  
• date
  Display date and time.
• command line completion
  After typing part of a command or a path, hit the TAB key, and the Linux-Bash shell will auto complete what you're typing, or auto complete the path that your typing in! Try typing "cd /ho" and then hit the TAB key. It fills in "cd /home/", now add to that path "ht" and TAB... Now it gives you "cd /home/httpd/"! This and the "pwd" command allow you to move around the various paths of a machine faster that you can point and click in Windows Explorer! Give it a try.