Basic Unix Shell commands

04 Jul

Create Directory Command:

Don’t forget, UNIX is case sensitive, UPPER CASE directory names are considered to be different from lower case directory names.

mkdir test2    creates a subdirectory called test2
mkdir /tmp/test2    makes a directory called test2 the /tmp directory
rmdir test2    removes an empty directory called test2

NOTE : The rmdir command will remove a directory only when empty. To remove a full directory and all it’s contents, use the below command.

rm -r directory_name

Shutdown Command:

The shutdown command can be used to turn off or reboot a computer. Type the command as follows to shutdown server / computer immediately:

Login as root user and type the command in terminal prompt

$ shutdown -h now
$ shutdown -h 0

Shutdown compute at specific time, To shutdown computer at 6:45pm.

$ shutdown -h 18:45 "Server is going down for maintenance"

At 6:30pm message will go out to all user and 6:45 system will shutdown.

Please note that you can also use halt or poweroff or reboot command for stopping and restarting the system:

$ halt
$ poweroff

Reboot computer:

$ reboot
$ shutdown -r 0

Remove file / directory command:

Remove command deletes files in a directory.  Remove command will not produce an output unless you have an error.

NOTE: There is no “undelete” command in UNIX,  once you delete a file, it is gone (unless it is on a backup tape).  Because of this, the rm command on CMGM and PMGM will ask you if you really want to delete a file before it goes ahead and does it.

Most UNIX commands have a variety of additional command modifiers that can be used to change the output. For example, if you typed

rm -r *

you would delete recursively the contents of a directory. This means the contents of a directory and all directories and files under it.

rm *    delete everything in a subdirectory
rm *.txt    remove only files with a .txt on the end
rm data*    remove only files that start with the word "data"
rm -r dir2    removes everything in the subdirectory "dir2"

Copy file / folder command:

Copy command lets you copy a file from one location to another on a UNIX machine.

cp -r * /tmp   copy everything in the directory to the /tmp directory
cp file1 file2    copy file1 to a file called file2
cp file1 /tmp     copy file1 to the /tmp directory
cp file1 ~smith    copy file1 to the home directory of "smith"

Move file / folder command:

move command is similar to the copy command, except it copies the file and deletes the original.

mv file1 file2    rename file1 to the name file2.
mv file1 /tmp    move file1 to the /tmp directory.
mv file1 ~sathu    move file1 to the home directory of "sathu".
mv * /tmp    move everything in the directory to the /tmp directory.
mv dir2 /tmp move the directory called dir2,and everything in it,
 to the /tmp directory.
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Posted by on July 4, 2012 in CentOS, General, Ubuntu


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