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Basic Linux Commands

1. pwd  Command

It stands for print working directory, It simply print the absolute path name of your current working directory

example-pwd

2. cd command

Change directory and it simply change your current directory to this Desktop directory

example-cd /Directory_path 

              cd /home/goeduhub/Desktop 

 cd / Changes to your root directory

cd ~ Changes to your home directory 

cd .. Changes to your parent directory

3.    ls : list directory contents

(The ls command will show you the list of files in your current directory.)

# ls

4. cp Command

The cp command copies files or directories. It can be used in two different ways: 

 Way #1 

cp file1 file2 

This will make a copy of file1 named file2. cp ­R dir1 dir2 This will make a copy of dir1 named dir2 (Assuming that dir2 didn't exist) 

Way #2 

cp file1 file2 ..... destination (directory) (Must exist) This will copy multiple files (file1, file2, ... ) into the destination  directory. 

cp ­R dir1 dir2 ..... destination (directory) (Must exist) This will copy multiple directories into the destination directory 

5. Make a directory 

If you want to create a directory, then you use mkdir command as follows 

mkdir directoryname 

You can create more than one directory as follows 

mkdir directory1 directory2 directory3 

This will create three directories 

mkdir stands for make directory 

 As you can see, Linux command names are logical. And that's why they are so easy to remember

6. Remove an empty directory

Now if you want to delete an empty directory  (For example, directory1) Then you use rmdir command as follows

 rmdir directory1 

This will only remove directory1 if it's empty ! You can also remove more than one empty directory at once. (For example,  directory1 directory2 directory3) 

rmdir directory1 directory2 directory3 

This will only remove directory1, directory2 and directory3 if they are all  empty . However, if directory1 and directory2 are non empty and directory3 is empty.  Then the above command will only delete directory3 and so on. Basically, It just deletes the empty directories. 

 rmdir stands for remove directory 

7. Touch Command

The touch command is the easiest way to create new, empty files. If you want to create an empty file (not a directory) then you just type  

touch yourfilename 

You can also create multiple files at the same time. For example  

touch file1 file2 file3

 will create 3 new empty files named file1,file2 and file3 respectively. Another use for the touch command touch is also used to update the timestamp (Modification date) for an existing file. For example if you already have a file named oldfile then  

touch oldfile  will change the timestamp of oldfile to the current time. Similarily  touch oldfile1 oldfile2 oldfile3  will change the timestamp of oldfile1,oldfile2 and oldfile3 to the current time.


Command Utility

Listing files inside a directory-

ls -l  List the files and directories in the current directory in long (table) format (It is recommended to

use -l with ls for better readability).

ls -ld dir-name    List information about the directory dir-name instead of its contents.

ls -a                      List all the files including the hidden ones (File names starting with a . are hidden files in Linux).

ls -F                       Appends a symbol at the end of a file name to indicate its type (* means executable, / means directory, @ means symbolic link, = means socket, | means named pipe, > means door).

ls -lt                     List the files sorted by last modified time with most recently modified files showing at the top (remember -l option provides the long format which has better readability).

ls -lh                    List the file sizes in human readable format.

ls -lR                      Shows all subdirectories recursively.

tree                       Will generate a tree representation of the file system starting from the current directory.


File/directory create, copy and remove

Command                                                          Utility

cp -p source destination

Will copy the file from source to destination. -p stands for preservation. It

preserves the original attributes of file while copying like file owner, timestamp,

group, permissions etc.

cp -R source_dir destination_dir 

Will copy source directory to specified destination recursively.

mv file1 file2 

In Linux there is no rename command as such. Hence mv moves/renames the

file1 to file2.

rm -i filename

Asks you before every file removal for confirmation. IF YOU ARE A NEW USER

TO LINUX COMMAND LINE, YOU SHOULD ALWAYS USE rm -i. You can specify

multiple files.

rm -R dir-name 

Will remove the directory dir-name recursively.

rm -rf dir-name

Will remove the directory dir recursively, ignoring non-existent files and will

never prompt for anything. BE CAREFUL USING THIS COMMAND! You can

specify multiple directories.

rmdir dir-name 

Will remove the directory dir-name, if it's empty. This command can only remove

empty directories.

mkdir dir-name 

Create a directory dir-name.

mkdir -p dir-name/dir-name

 Create a directory hierarchy. Create parent directories as needed, if they don't

exist. You can specify multiple directories.


File/directory permissions and groups

Command                                                                          Utility

chmod <specification> filename 

Change the file permissions. Specifications = u user, g group, o other, + add

permission, - remove, r read, w write,x execute.

chmod -R <specification> dirname

Change the permissions of a directory recursively. To change permission of

a directory and everything within that directory, use this command.

chmod go=+r myfile 

Add read permission for the owner and the group.

chmod a +rwx myfile 

Allow all users to read, write or execute myfile.

chmod go -r myfile 

Remove read permission from the group and others.

chown owner1 filename 

Change ownership of a file to user owner1.

chgrp grp_owner filename 

Change primary group ownership of file filename to group grp_owner.

chgrp -R grp_owner dir-name

Change primary group ownership of directory dir-name to group grp_owner

recursively. To change group ownership of a directory and everything within

that directory, use this command.

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