| Linux command | Description | 
  
    | pgm  | start pgm where pgm is a program found in the $PATH | 
  
    | ./pgm | start pgm (allocated in current dir.) | 
  
    | cd x or cd /x | go to directory x | 
  
    | cd .. or cd ../ or cd /.. | go back one directory | 
  
    | ls or dir | list a directory | 
  
    | cat | display a textfile on the terminal | 
  
    | mv x y | move or rename file x to file y | 
  
    | cp x y | copy file x to file y | 
  
    | rm x | delete a file | 
  
    | mkdir x | make a directory | 
  
    | rmdir x | remove a directory | 
  
    | rm -r x | remove directory x and all its underlying files | 
  
    | df or df x | Show free space on device x | 
  
    | top | view memory status (q to quit) | 
  
    | man x | get a manual page about command x | 
  
    | less x or more x | view text file x | 
  
    | echo | print something on the screen mainly used in scripts | 
  
    | mc | similar to Norton Commander in DOS | 
  
    | mount | to make a device usable to the system (CD-ROM,other HD) | 
  
    | umount | umount to remove the device from being usable to the system | 
  
    | halt | to shutdown. It will also power off if APM or ACPI is being used | 
  
    | reboot | to reboot the system | 
  
    | chmod <permissions> <file> | change file permissions | 
  
    | chown <owner:group> <file> | change file ownership | 
  
    | ls -l x | perform a detailed directory listing for file or directory x | 
  
    | ln -s x y | make a symbolic link to x called y | 
  
    | find x -name y -print | find file y, begin the search from within directory x and print the results to screen | 
  
    | ps | to view all running processes | 
  
    | kill x | to terminate process x (x is PID from ps) | 
  
    | killall -KILL pgm | to kill the program called pgm | 
  
    | killall -HUP pgm | to force program pgm to restart - used in case configuration is changed | 
  
    | [alt] + F1 - F7 | switch to terminal 1 - 7 | 
  
    | lilo | to write boot information changes to disk | 
  
    | startx | to start the XFree86 GUI | 
  
    | Directories | Function | 
  
    | / | the root of the directory tree this is the base | 
  
    | /dev | the device pointer directory all devices have an entry here | 
  
    | /bin | main CLI executables | 
  
    | /sbin | main CLI system executables | 
  
    | /boot | location of the kernel and boot information required to boot the system | 
  
    | /etc | system configuration files | 
  
    | /root | root user home directory | 
  
    | /home | normal user base directory | 
  
    | /lib | system libraries and kernel modules | 
  
    | /usr | main user binary,documentation, library location | 
  
    | /opt | extra binary/documentation,library location - eg. KDE,Gnome | 
  
    | /var | system log files,spoolers,etc | 
  
    | /tmp | temporary folder for running applications that need temp files | 
  
    | /proc | proc filesystem for kernel interaction - this is everything the kernel knows | 
  
    | /mnt | filesystem mount point for extra devices and drives | 
              
                | Important Configuration Files | Function | 
              
                | /etc/lilo.conf | boot loader configuration file - you must run "lilo" after any changes | 
              
                | /etc/modules.conf | kernel module loader configuration used by the modprobe command | 
              
                | /etc/inittab | system runlevel configuration file - tells init what to do for each runlevel | 
              
                | /etc/fstab | filesystem mounting configuration file - used by the mount command | 
              
                | /etc/ld.so.conf | library configuration file - used by the ldconfig command to find libraries | 
              
                | /etc/inetd.conf | tcp wrapper configuration - used to start ftp and other network daemons | 
              
                | /etc/hosts | local host resolution file | 
              
                | /etc/HOSTNAME | system hostname file | 
              
                | /etc/profile | system defaults for bash login default paths,colours,etc | 
              
                | /etc/rc.d/rc.0 | system halt script - run when you issue halt | 
              
                | /etc/rc.d/rc.K | system reboot script - run when you issue reboot or [ctrl] + [alt] + [del] | 
              
                | /etc/rc.d/rc.S | main system boot script - run when you boot up | 
              
                | /etc/rc.d/rc.M | main local startup script - activates other services you have chosen | 
              
                | /etc/rc.d/rc.X | GUI startup script used when runlevel 5 is selected in /etc/inittab | 
              
                | /etc/rc.d/rc.sysvinit | SysV Init script starter | 
              
                | /etc/rc.d/rc.inet1 | network startup script | 
              
                | /etc/rc.d/rc.netdevice | network card module loader - newer versions will just be added to modules.conf | 
              
                | /etc/rc.d/rc.modules | system module loader - run at startup | 
              
                | /etc/rc.d/rc.hotplug | hotplug starter script - for USB and PCI hotplug devices | 
              
                | /etc/rc.d/rc.pcmcia | pcmcia service script - for use with laptops | 
              
                | /etc/rc.d/rc.local | local startup script for user space programs | 
              
                | /etc/XF86Config | XFree86 3.3.6 configuration file | 
              
                | /etc/X11/XF86Config-4 | XFre86 4.2.1 configuration file |