Basic Linux Commands

Basic Linux Commands

Command                  Example                                            Description

cat           Sends file contents to standard output. This is a way to list the contents of short files to the screen. It works well with piping.

       cat .bashrc   Sends the contents of the ".bashrc" file to the screen.

cd            Change directory

       cd /home      Change the current working directory to /home. The '/' indicates relative to root, and no matter what directory you are in when you execute this command, the directory will be changed to "/home".

      

cd httpd      Change the current working directory to httpd, relative to the current location which is "/home". The full path of the new working directory is "/home/httpd".

      

cd ..  Move to the parent directory of the current directory. This command will make the current working directory "/home.

      

cd ~   Move to the user's home directory which is "/home/username". The '~' indicates the users home directory.

cp            Copy files

       cp myfile yourfile   Copy the files "myfile" to the file "yourfile" in the current working directory. This command will create the file "yourfile" if it doesn't exist. It will normally overwrite it without warning if it exists.

      

cp -i myfile yourfile      With the "-i" option, if the file "yourfile" exists, you will be prompted before it is overwritten.

      

cp -i /data/myfile . Copy the file "/data/myfile" to the current working directory and name it "myfile". Prompt before overwriting the file.

      

cp -dpr srcdir destdir     Copy all files from the directory "srcdir" to the directory "destdir" preserving links (-p option), file attributes (-p option), and copy recursively (-r option). With these options, a directory and all it contents can be copied to another directory.

dd     dd if=/dev/hdb1 of=/backup/       Disk duplicate. The man page says this command is to "Convert and copy a file", but although used by more advanced users, it can be a very handy command. The "if" means input file, "of" means output file.

df            Show the amount of disk space used on each mounted filesystem.

less   less textfile Similar to the more command, but the user can page up and down through the file. The example displays the contents of textfile.

ln            Creates a symbolic link to a file.

       ln -s test symlink   Creates a symbolic link named symlink that points to the file test Typing "ls -i test symlink" will show the two files are different with different inodes. Typing "ls -l test symlink" will show that symlink points to the file test.

locate        A fast database driven file locator.

       slocate -u    This command builds the slocate database. It will take several minutes to complete this command. This command must be used before searching for files, however cron runs this command periodically on most systems.

       locate whereis       Lists all files whose names contain the string "whereis".

logout        Logs the current user off the system.

ls            List files

       ls     List files in the current working directory except those starting with . and only show the file name.

       ls -al List all files in the current working directory in long listing format showing permissions, ownership, size, and time and date stamp

more          Allows file contents or piped output to be sent to the screen one page at a time.

       more /etc/profile    Lists the contents of the "/etc/profile" file to the screen one page at a time.

      

ls -al |more  Performs a directory listing of all files and pipes the output of the listing through more. If the directory listing is longer than a page, it will be listed one page at a time.

mv            Move or rename files

       mv -i myfile yourfile      Move the file from "myfile" to "yourfile". This effectively changes the name of "myfile" to "yourfile".

      

mv -i /data/myfile . Move the file from "myfile" from the directory "/data" to the current working directory.

pwd           Show the name of the current working directory

       more /etc/profile    Lists the contents of the "/etc/profile" file to the screen one page at a time.

shutdown             Shuts the system down.

       shutdown -h now      Shuts the system down to halt immediately.

       shutdown -r now      Shuts the system down immediately and the system reboots.

whereis              Show where the binary, source and manual page files are for a command

       whereis ls    Locates binaries and manual pages for the ls command.