Tuesday, December 29, 2009

LINUX BASIC COMMANDS



Navigation Commands - [ pwd, cd ]


pwd
 This command is used to find the current location or current working directory.

 Eg:
 [user@ws26 ~]$ pwd
 /home/user

 cd
 This command id used to change the directory. You can move from one directory to another using this command. Few examples are given below.

 Concider you have a directory structure /home/user/test/test1/ . test and test1 are directories in user home.

 Example 1:
 Consider you have a directory "test" in /home/user. Your current working directory is /home/user. You want to change your current working directory from /home/user to /home/user/test, use the following command
 [user@ws26 ~]$ pwd
 /home/user
 [user@ws26 ~]$ cd test
 [user@ws26 ~]$ pwd
 /home/user/test

 Example 2:
 If you want to move back to /home/user, use the following command
 [user@ws26 ~]$ cd ..
 [user@ws26 ~]$ pwd
 /home/user

 Example 3:
 To get back to the home directory of the user
 [user@ws26 ~]$ cd ~
 [user@ws26 ~]$ pwd
 /home/user.




Listing contents in a directory - [ ls, ls -l, ll ]


ls
 This command is used to list all the files and directory in the current directory.

 Eg:
 [user@ws26 ~]$ ls
 1152696870.jpg book OperaDownloads snapshot52.png
 image300.jpg Desktop test spiderman2.jpg

 ls -l or ll
 This command is also used to list all the files and directories. Here you will get more details about the files and directories present in the current directory. You will see the permission set, creation date, file / directory size etc.

 Eg:
 [user@ws26 ~]$ ls -l
 total 5
 -rw-rw-r-- 1 user user 33188 Dec 22 02:56 1152696870.jpg
 -rw-rw-r-- 1 user user 17647 Aug 19 2006 534458.gif
 -rw-rw-r-- 1 user user 26817 Aug 19 2006 534477.gif
 drwxrwxr-x 2 user user 4096 Jan 13 04:20 book
 drwx------ 3 user user 4096 Feb 4 02:34 Desktop




Reading files in Linux - [ cat, more, less ]


Cat
 This command is used to display the contents of a file. You can read the file contents using the cat command.

 Example:
 [user@ws26 ~]$ cat testfile
 this is a test file.. You can read me..


 Less and More
 Both the less and more commands serve similar function. They are used to display file one screen at a time. You can press spacebar to continue reading the file. These commands are mainly used while reading large files.

 Example 1:
 [user@ws26 ~]$ less testfile
 this is a test file.. You can read me..

 Example 2:
 [user@ws26 ~]$ more testfile
 this is a test file.. You can read me..


manipulating files - [ cp, mv, rm, mkdir ]


cp
 This command is used to copy files/directory.

 Example:
 [user@ws26 ~]$ cp file1 directory1
 This will copy the file1 into the directory1

 cp -R
 This command is used to copy directories recursively (copy all the files and folders inside the directory).

 Example:
 [user@ws26 ~]$ cp directory2 directory1
 This will copy the whole directory2 into directory1

 mv
 This command is used to move the file or directory.

 Example:
 [user@ws26 ~]$ mv directory2 directory1
 This will move the whole directory2 into directory1

 rm
 This command is used to remove or delete files and directories.

 Example:
 [user@ws26 ~]$ rm directory2
 This will delete the directory - directory2

 mkdir
 This command is used to create a new directory

 Example:
 [user@ws26 ~]$ mkdir directory3
 This will create a new directory - directory3.

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