In this post we will see all linux commands with detailed examples.
I sincerely thank Sushree Satapathy for her time and efforts for contributing this article and open source community.
whatis
Display one-line manual page descriptions
sushree@Sushree:/$ whatis pwd
pwd (1) - print name of current/working directory
whereis
To find the source, binary, and manuals sections for specified commands or files
sushree@Sushree:~/Desktop/opensourcetutorial$ whereis ls
ls: /bin/ls /usr/share/man/man1/ls.1.gz
who
Shows who is logged on
sushree@Sushree:/$ who
sushree :0 2019-02-10 11:52 (:0)
sushree pts/0 2019-02-10 12:46 (:0)
who am i
Print the user name associated with the current effective user ID.
sushree@Sushree:/$ who am i
sushree pts/0 2019-02-10 12:46 (:0)
cat
Concatenate files and print on the standard output
SYNTAX : cat [OPTION]… [FILE]…
sushree@Sushree:~/Desktop/opensourcetutorial$ ls
hello.txt hello.txt~ welcome.txt welcome.txt~
sushree@Sushree:~/Desktop/opensourcetutorial$ cat hello.txt welcome.txt
Hello World..!!
Welcome to www.opensourcetutorials.in
cal
Displays a calendar
sushree@Sushree:~/Desktop/opensourcetutorial$ cal
February 2019
Su Mo Tu We Th Fr Sa
1 2
3 4 5 6 7 8 9
10 11 12 13 14 15 16
17 18 19 20 21 22 23
24 25 26 27 28
pwd
Print name of current/working directory
SYNTAX : pwd [OPTION]…
sushree@Sushree:~$ pwd
/home/sushree
ls
List directory contents
SYNTAX : ls [OPTION]… [FILE]…
sushree@Sushree:~$ ls
Desktop Downloads Music Public Videos
Documents examples.desktop Pictures Templates VirtualBox VMs
Note : The directories are listed in lexicographical order.
-r
reverse order while sorting
sushree@Sushree:~$ ls -r
VirtualBox VMs Templates Pictures examples.desktop Documents
Videos Public Music Downloads Desktop
-l
use a long listing format
sushree@Sushree:~$ ls -l
total 48
drwxr-xr-x 2 sushree sushree 4096 Jan 18 12:14 Desktop
drwxr-xr-x 2 sushree sushree 4096 Aug 10 2018 Documents
drwxr-xr-x 3 sushree sushree 4096 Feb 5 23:07 Downloads
-rw-r--r-- 1 sushree sushree 8980 May 12 2017 examples.desktop
drwxr-xr-x 2 sushree sushree 4096 May 12 2017 Music
drwxr-xr-x 2 sushree sushree 4096 Apr 16 2018 Pictures
drwxr-xr-x 2 sushree sushree 4096 May 12 2017 Public
drwxr-xr-x 2 sushree sushree 4096 May 12 2017 Templates
drwxr-xr-x 2 sushree sushree 4096 May 12 2017 Videos
drwxrwxr-x 4 sushree sushree 4096 Jan 21 22:36 VirtualBox VMs
The information can be broken down into ten fields as shown below. Let us consider the Desktop directory.
drwxr-xr-x 2 sushree sushree 4096 Jan 18 12:14 Desktop
| Detail | Description |
|---|---|
| d | file type |
| rwx | owner’s mode of access(permission) |
| r-x | group’s mode of access(permission) |
| r-x | other’s mode of access(permission) |
| 2 | number of hard links |
| sushree | owner of the file |
| sushree | group of the file |
| 4096 | size of the file in bytes |
| Aug 10 2018 | last modified time stamp |
| Desktop | Name |
**d**rwxr-xr-x 2 sushree sushree 4096 Jan 18 12:14 Desktop
The first field file type can be of the following types:
| Detail | FileType | Description |
|---|---|---|
| d | Directory | A file used to store other files. |
| - | Regular file | Includes readable files, images files, binary files, and compressed files. |
| l | Symbolic link | Points to another file. |
| s | Socket | Allows for communication between processes.(duplex) |
| p | Pipe | Allows for communication between processes executed under different user names and permission.(unidirectional) |
| b | Block file | Used to communicate with hardware.(read/write data in blocks) |
| c | Character file | Used to communicate with hardware.(read/write data character by character) |
The next nine set of characters indicate the permissions/mode of access o the file. There are three different types of permissions as shown below Permission | Effect on file | Effects on directory
| Permisson | Use | Description |
|---|---|---|
| Read ( r ) | Allows for file contents to be read or copied. | Without execute permission on the directory, allows for a non-detailed listing of files. With execute permission, ls -l can provide a detailed listing. |
| Write ( w ) | Allows for contents to be modified or overwritten. Allows for files to be added or removed from a directory. | For this permission to work, the directory must also have execute permission. |
| Execute( x) | Allows for a file to be run as a process, although script files require read permission, as well. | Allows a user to change to the directory if parent directories have write permission as well. |
The nine characters can be broken down into sets of three. They correspond to the owner of the file, the group that own’s the file and others(excluding the owner and the group)
In case of the Desktop directory, the owner has read, write and execute permission, the group which owns the directory has read and execute permission & the others have read and execute permission.
drwxr-xr-x 2 sushree sushree 4096 Jan 18 12:14 Desktop
The next field indicates the number of hard links to the file.
drwxr-xr-x 2 sushree sushree 4096 Jan 18 12:14 Desktop
The next field indicates the owner of the file.
drwxr-xr-x 2 sushree sushree 4096 Jan 18 12:14 Desktop
The next field indicates the group that owns the file.
drwxr-xr-x 2 sushree sushree 4096 Jan 18 12:14 Desktop
The field that follows is the size of the file in bytes.
drwxr-xr-x 2 sushree sushree 4096 Jan 18 12:14 Desktop
The next field is the last modified date of thee file.
drwxr-xr-x 2 sushree sushree 4096 Jan 18 12:14 Desktop
The last field is the name of file.
Linux command options can be combined without a space between them and with a single - (dash).
The following are the file types
-lr
Long listing format in the reverse order
sushree@Sushree:~$ ls -lr
total 48
drwxrwxr-x 4 sushree sushree 4096 Jan 21 22:36 VirtualBox VMs
drwxr-xr-x 2 sushree sushree 4096 May 12 2017 Videos
drwxr-xr-x 2 sushree sushree 4096 May 12 2017 Templates
drwxr-xr-x 2 sushree sushree 4096 May 12 2017 Public
drwxr-xr-x 2 sushree sushree 4096 Apr 16 2018 Pictures
drwxr-xr-x 2 sushree sushree 4096 May 12 2017 Music
-rw-r--r-- 1 sushree sushree 8980 May 12 2017 examples.desktop
drwxr-xr-x 3 sushree sushree 4096 Feb 5 23:07 Downloads
drwxr-xr-x 2 sushree sushree 4096 Aug 10 2018 Documents
drwxr-xr-x 2 sushree sushree 4096 Jan 18 12:14 Desktop
Note : The order of the options doesnot affect the output.
sushree@Sushree:~$ ls -rl
total 48
drwxrwxr-x 4 sushree sushree 4096 Jan 21 22:36 VirtualBox VMs
drwxr-xr-x 2 sushree sushree 4096 May 12 2017 Videos
drwxr-xr-x 2 sushree sushree 4096 May 12 2017 Templates
drwxr-xr-x 2 sushree sushree 4096 May 12 2017 Public
drwxr-xr-x 2 sushree sushree 4096 Apr 16 2018 Pictures
drwxr-xr-x 2 sushree sushree 4096 May 12 2017 Music
-rw-r--r-- 1 sushree sushree 8980 May 12 2017 examples.desktop
drwxr-xr-x 3 sushree sushree 4096 Feb 5 23:07 Downloads
drwxr-xr-x 2 sushree sushree 4096 Aug 10 2018 Documents
drwxr-xr-x 2 sushree sushree 4096 Jan 18 12:14 Desktop
-t
sort by modification time, newest first
sushree@Sushree:~$ ls -lt
total 48
drwxr-xr-x 3 sushree sushree 4096 Feb 5 23:07 Downloads
drwxrwxr-x 4 sushree sushree 4096 Jan 21 22:36 VirtualBox VMs
drwxr-xr-x 2 sushree sushree 4096 Jan 18 12:14 Desktop
drwxr-xr-x 2 sushree sushree 4096 Aug 10 2018 Documents
drwxr-xr-x 2 sushree sushree 4096 Apr 16 2018 Pictures
drwxr-xr-x 2 sushree sushree 4096 May 12 2017 Music
drwxr-xr-x 2 sushree sushree 4096 May 12 2017 Public
drwxr-xr-x 2 sushree sushree 4096 May 12 2017 Templates
drwxr-xr-x 2 sushree sushree 4096 May 12 2017 Videos
-rw-r--r-- 1 sushree sushree 8980 May 12 2017 examples.desktop
-lrt
sort by modification time and reverse order for the same modification time stamp
sushree@Sushree:~$ ls -lrt
total 48
-rw-r--r-- 1 sushree sushree 8980 May 12 2017 examples.desktop
drwxr-xr-x 2 sushree sushree 4096 May 12 2017 Videos
drwxr-xr-x 2 sushree sushree 4096 May 12 2017 Templates
drwxr-xr-x 2 sushree sushree 4096 May 12 2017 Public
drwxr-xr-x 2 sushree sushree 4096 May 12 2017 Music
drwxr-xr-x 2 sushree sushree 4096 Apr 16 2018 Pictures
drwxr-xr-x 2 sushree sushree 4096 Aug 10 2018 Documents
drwxr-xr-x 2 sushree sushree 4096 Jan 18 12:14 Desktop
drwxrwxr-x 4 sushree sushree 4096 Jan 21 22:36 VirtualBox VMs
drwxr-xr-x 3 sushree sushree 4096 Feb 5 23:07 Downloads
cd
Change the shell working directory
SYNTAX : cd [options] [path]
sushree@Sushree:~$ pwd
/home/sushree
sushree@Sushree:~$ ls
Desktop Downloads Music Public Videos
Documents examples.desktop Pictures Templates VirtualBox VMs
sushree@Sushree:~$ cd Desktop
sushree@Sushree:~/Desktop$ pwd
/home/sushree/Desktop
cd ..
Change the shell to parent directory
sushree@Sushree:~/Desktop$ pwd
/home/sushree/Desktop
sushree@Sushree:~/Desktop$ cd ..
sushree@Sushree:~$ pwd
/home/sushree
cd ~
Change directory to the home directory of the current user
sushree@Sushree:~/Desktop/opensourcetutorial$ pwd
/home/sushree/Desktop/opensourcetutorial
sushree@Sushree:~/Desktop/opensourcetutorial$ cd ~
sushree@Sushree:~$ pwd
/home/sushree
cd using absolute path
sushree@Sushree:~$ pwd
/home/sushree
sushree@Sushree:~$ cd /home/sushree/Desktop/opensourcetutorial/
sushree@Sushree:~/Desktop/opensourcetutorial$ pwd
/home/sushree/Desktop/opensourcetutorial
cd using relative path
sushree@Sushree:~$ pwd
/home/sushree
sushree@Sushree:~$ cd Desktop/opensourcetutorial/
sushree@Sushree:~/Desktop/opensourcetutorial$ pwd
/home/sushree/Desktop/opensourcetutorial
cd command
Change directory two directories up
sushree@Sushree:~$ cd Desktop/opensourcetutorial/
sushree@Sushree:~/Desktop/opensourcetutorial$ cd ../../
sushree@Sushree:~$ pwd
/home/sushree
sushree@Sushree:~$
chmod
Change the file permissions (mode of access)
There are two techniques
1. Symbolic Method
SYNTAX : chmod []… FILE
Use combinations of letters and symbols to add or remove permissions.
The who are indicated using the following characters
| Symbol | Meaning |
|---|---|
| u | User: The user who owns the file. |
| g | Group: The group who owns the file. |
| o | Others: Anyone other than the user owner or member of the group owner. |
| a | All: Refers to the user, group and others. |
The operators can be indicated using the following characters
| Symbol | Meaning |
|---|---|
| + | Add the permission |
| = | Assign the permission |
| - | Remove the permission |
The permissions can be indicated using the following characters
| Symbol | Meaning |
|---|---|
| r | read |
| w | write |
| x | execute |
The option will be followed by the path to the file whose permission is to be modified.
sushree@Sushree:~/Desktop/opensourcetutorial$ ls -l
total 4
drwxrwxr-x 2 sushree sushree 4096 Feb 10 23:42 sush.txt
sushree@Sushree:~/Desktop/opensourcetutorial$ chmod u-w sush.txt
sushree@Sushree:~/Desktop/opensourcetutorial$ ls -l
total 4
dr-xrwxr-x 2 sushree sushree 4096 Feb 10 23:42 sush.txt
2. Absolute Method
SYNTAX : chmod [OPTION]… OCTAL-MODE FILE…
Use numbers to represent the permissions where each triplet is an octal number
The following is the list of octal values for setting the file permissions
| Octal Value | File Permissions Set | Permissions Description |
|---|---|---|
| 0 | — | No permissions |
| 1 | –x | Execute permission only |
| 2 | -w- | Write permission only |
| 3 | -wx | Write and execute permissions |
| 4 | r– | Read permission only |
| 5 | r-x | Read and execute permissions |
| 6 | rw- | Read and write permissions |
| 7 | rwx | Read, write, and execute permissions |
sushree@Sushree:~/Desktop/opensourcetutorial$ ls -l
total 4
dr-xrwxr-x 2 sushree sushree 4096 Feb 10 23:42 sush.txt
sushree@Sushree:~/Desktop/opensourcetutorial$ chmod 775 sush.txt
sushree@Sushree:~/Desktop/opensourcetutorial$ ls -l
total 4
drwxrwxr-x 2 sushree sushree 4096 Feb 10 23:42 sush.txt
The octal nnumber 775 represents rwx rwx r-x. Therefore, the users gets the write access back.
chown
Change file owner and group
Changing ownership requires administrative access. Even an owner does noot have the right to give ownership of his file to another user. However, group ownership does not require administrative rights.
SYNTAX : chown [OPTIONS] [OWNER] FILE
Changing user ownership
sushree@Sushree:~/Desktop/opensourcetutorial$ ls -l
total 8
-rw-rw-r-- 1 sushree sushree 16 Feb 11 00:49 hello.txt
-rw-rw-r-- 1 sushree sushree 38 Feb 11 00:49 welcome.txt
sushree@Sushree:~/Desktop/opensourcetutorial$ sudo su
[sudo] password for sushree:
root@Sushree:/home/sushree/Desktop/opensourcetutorial# chown root hello.txt
root@Sushree:/home/sushree/Desktop/opensourcetutorial# ls -l
total 8
-rw-rw-r-- 1 root sushree 16 Feb 11 00:49 hello.txt
-rw-rw-r-- 1 sushree sushree 38 Feb 11 00:49 welcome.txt
Changing group ownership
root@Sushree:/home/sushree/Desktop/opensourcetutorial# ls -l
total 8
-rw-rw-r-- 1 sushree sushree 16 Feb 11 00:49 hello.txt
-rw-rw-r-- 1 sushree sushree 38 Feb 11 00:49 welcome.txt
root@Sushree:/home/sushree/Desktop/opensourcetutorial# chown root:root hello.txtroot@Sushree:/home/sushree/Desktop/opensourcetutorial# ls -l
total 8
-rw-rw-r-- 1 root root 16 Feb 11 00:49 hello.txt
-rw-rw-r-- 1 sushree sushree 38 Feb 11 00:49 welcome.txt
mv
It is a file management command used to Rename SOURCE to DEST, or move SOURCE(s) to DIRECTORY.
SYNTAX : mv SOURCE DESTINATION
The mv command requires two arguments. The first argument is the path of the file to be moved (source) and the second is the path where the file is to be moved (destination).
If the file is moved from source to destination without specfying a new name, it will retain its old name.
sushree@Sushree:~/Desktop$ ls
opensourcetutorial osgeolive-12.0-vm.7z osgeolive-12.0-vm.vmdk
sushree@Sushree:~/Desktop$ cd opensourcetutorial/
sushree@Sushree:~/Desktop/opensourcetutorial$ ls
hello.txt welcome.txt
sushree@Sushree:~/Desktop/opensourcetutorial$ mv hello.txt /home/sushree/Desktop/
sushree@Sushree:~/Desktop/opensourcetutorial$ cd ..
sushree@Sushree:~/Desktop$ ls
hello.txt opensourcetutorial osgeolive-12.0-vm.7z osgeolive-12.0-vm.vmdk
however, the file can be renamed using the mv command by specifying the new name in the destination argument.
sushree@Sushree:~/Desktop$ ls
hello.txt opensourcetutorial osgeolive-12.0-vm.7z osgeolive-12.0-vm.vmdk
sushree@Sushree:~/Desktop$ mv hello.txt /home/sushree/Desktop/opensourcetutorial/newhello.txt
sushree@Sushree:~/Desktop$ cd opensourcetutorial/
sushree@Sushree:~/Desktop/opensourcetutorial$ ls
newhello.txt welcome.txt
Moving the file in the same directory will result in renaming the file.
sushree@Sushree:~/Desktop/opensourcetutorial$ ls
newhello.txt welcome.txt
sushree@Sushree:~/Desktop/opensourcetutorial$ mv newhello.txt rename.txt
sushree@Sushree:~/Desktop/opensourcetutorial$ ls
rename.txt welcome.txt
Multiple files can be moved using the mv command
sushree@Sushree:~/Desktop/opensourcetutorial$ ls
rename.txt welcome.txt
sushree@Sushree:~/Desktop/opensourcetutorial$ mv rename.txt welcome.txt /home/sushree/Desktop/
sushree@Sushree:~/Desktop/opensourcetutorial$ ls
sushree@Sushree:~/Desktop/opensourcetutorial$ cd ..
sushree@Sushree:~/Desktop$ ls
opensourcetutorial osgeolive-12.0-vm.vmdk welcome.txt
osgeolive-12.0-vm.7z rename.txt
mv command requires write and execute permission on both the source and destination.
sushree@Sushree:~/Desktop$ ls -l
total 14118052
-rw-rw-r-- 1 sushree sushree 17 Feb 17 21:07 hello.txt
drwxrwxr-x 2 sushree sushree 4096 Feb 17 21:11 opensourcetutorial
-rw-r--r-- 1 sushree sushree 3359521331 Jan 16 07:28 osgeolive-12.0-vm.7z
-rw------- 1 sushree sushree 11097341952 Jan 21 22:35 osgeolive-12.0-vm.vmdk
-rw-rw-r-- 1 sushree sushree 38 Feb 11 00:49 welcome.txt
sushree@Sushree:~/Desktop$ mv hello.txt /home/sushree/Desktop/opensourcetutorial/hello.txt
sushree@Sushree:~/Desktop$ ls -l
total 14118048
drwxrwxr-x 2 sushree sushree 4096 Feb 17 21:12 opensourcetutorial
-rw-r--r-- 1 sushree sushree 3359521331 Jan 16 07:28 osgeolive-12.0-vm.7z
-rw------- 1 sushree sushree 11097341952 Jan 21 22:35 osgeolive-12.0-vm.vmdk
-rw-rw-r-- 1 sushree sushree 38 Feb 11 00:49 welcome.txt
sushree@Sushree:~/Desktop$ chmod u-w opensourcetutorial/
sushree@Sushree:~/Desktop$ chmod u-x opensourcetutorial/
sushree@Sushree:~/Desktop$ ls -l
total 14118048
dr--rwxr-x 2 sushree sushree 4096 Feb 17 21:12 opensourcetutorial
-rw-r--r-- 1 sushree sushree 3359521331 Jan 16 07:28 osgeolive-12.0-vm.7z
-rw------- 1 sushree sushree 11097341952 Jan 21 22:35 osgeolive-12.0-vm.vmdk
-rw-rw-r-- 1 sushree sushree 38 Feb 11 00:49 welcome.txt
sushree@Sushree:~/Desktop$ mv welcome.txt /home/sushree/Desktop/opensourcetutorial/
mv: cannot stat ‘/home/sushree/Desktop/opensourcetutorial/welcome.txt’: Permission denied
cp
Copy SOURCE to DEST, or multiple SOURCE(s) to DIRECTORY.
SYNTAX : cp [OPTIONS] SOURCE DESTINATION
sushree@Sushree:~/Desktop$ ls -l
total 14118052
-rw-rw-r-- 1 sushree sushree 17 Feb 17 21:07 hello.txt
drwxrwxr-x 2 sushree sushree 4096 Feb 17 21:12 opensourcetutorial
-rw-r--r-- 1 sushree sushree 3359521331 Jan 16 07:28 osgeolive-12.0-vm.7z
-rw------- 1 sushree sushree 11097341952 Jan 21 22:35 osgeolive-12.0-vm.vmdk
-rw-rw-r-- 1 sushree sushree 38 Feb 11 00:49 welcome.txt
sushree@Sushree:~/Desktop$ cp hello.txt /home/sushree/Desktop/opensourcetutorial/
sushree@Sushree:~/Desktop$ cd opensourcetutorial/
sushree@Sushree:~/Desktop/opensourcetutorial$ ls
hello.txt
sushree@Sushree:~/Desktop$ ls -l
total 14118048
dr--rwxr-x 2 sushree sushree 4096 Feb 17 21:12 opensourcetutorial
-rw-r--r-- 1 sushree sushree 3359521331 Jan 16 07:28 osgeolive-12.0-vm.7z
-rw------- 1 sushree sushree 11097341952 Jan 21 22:35 osgeolive-12.0-vm.vmdk
-rw-rw-r-- 1 sushree sushree 38 Feb 11 00:49 welcome.txt
sushree@Sushree:~/Desktop$ cp /home/sushree/Desktop/opensourcetutorial/hello.txt /home/sushree/Desktop/
cp: cannot stat ‘/home/sushree/Desktop/opensourcetutorial/hello.txt’: Permission denied
rm
remove files or directories
SYNTAX : rm [OPTION]… FILE…
sushree@Sushree:~/Desktop$ ls
hello.txt osgeolive-12.0-vm.7z welcome.txt
opensourcetutorial osgeolive-12.0-vm.vmdk
sushree@Sushree:~/Desktop$ rm hello.txt
sushree@Sushree:~/Desktop$ ls
opensourcetutorial osgeolive-12.0-vm.7z osgeolive-12.0-vm.vmdk welcome.txt
date
Display the current time in the given FORMAT, or set the system date.
SYNTAX : date [OPTION]… [+FORMAT]
sushree@Sushree:~/Desktop$ date
Sun Feb 24 11:35:17 IST 2019
Display date in a given format
The following are the format specifier
| Format Specifier | Description |
|---|---|
| %D | Display date as mm/dd/yy. |
| %d | Display the day of the month (01 to 31). |
| %a | Displays the abbreviated name for weekdays (Sun to Sat). |
| %A | Displays full weekdays (Sunday to Saturday). |
| %h | Displays abbreviated month name (Jan to Dec). |
| %b | Displays abbreviated month name (Jan to Dec). |
| %B | Displays full month name(January to December). |
| %m | Displays the month of year (01 to 12). |
| %y | Displays last two digits of the year(00 to 99). |
| %Y | Display four-digit year. |
| %T | Display the time in 24 hour format as HH:MM:SS. |
| %H | Display the hour. |
| %M | Display the minute. |
| %S | Display the seconds. |
Display UTC(Coordinated Universal Time ) time
sushree@Sushree:~$ date -u
Sat Mar 30 04:15:45 UTC 2019
Display the date specified in the string in date format
sushree@Sushree:~$ date --date="09/20/2018"
Thu Sep 20 00:00:00 IST 2018
Here the date specified is 20th September 2018 which has been displayedd in the date format.
Displaying past date
sushree@Sushree:~$ date --date="1 year ago"
Fri Mar 30 09:54:23 IST 2018
sushree@Sushree:~$ date --date="5 secs ago"
Sat Mar 30 09:54:49 IST 2019
sushree@Sushree:~$ date --date="6 months ago"
Sun Sep 30 09:55:49 IST 2018
Displaying futre date
sushree@Sushree:~$ date --date="next monday"
Mon Apr 1 00:00:00 IST 2019
sushree@Sushree:~$ date --date="5 year"
Sat Mar 30 09:57:39 IST 2024
sushree@Sushree:~$ date --date="tomorrow"
Sun Mar 31 09:58:30 IST 2019
Set the system date
sushree@Sushree:~$ date --set="Tue Nov 13 15:23:34 UTC 2018"
sushree@Sushree:~$ date
Tue Nov 13 15:23:34 UTC 2018
#stat
Displays file status or inofrmation
sushree@Sushree:~/Desktop/opensourcetutorial$ stat a.txt
File: ‘a.txt’
Size: 0 Blocks: 0 IO Block: 4096 regular empty file
Device: 809h/2057d Inode: 2121285 Links: 1
Access: (0664/-rw-rw-r--) Uid: ( 1000/ sushree) Gid: ( 1000/ sushree)
Access: 2019-03-31 18:27:02.261105369 +0530
Modify: 2019-03-31 18:27:02.261105369 +0530
Change: 2019-03-31 18:27:02.261105369 +0530
Birth: -
It includes information like the name of the file, size, number of blocks it is using, inode number, number of hard links, last modified time, last access time etc.
touch
Touch command allows to create a blank file. In case if the file already exist it will change the access time of the file.
SYNTAX : touch [OPTION]… FILE…
To create an empty file
sushree@Sushree:~/Desktop/opensourcetutorial$ ls
hello.txt
sushree@Sushree:~/Desktop/opensourcetutorial$ touch welcome.txt
sushree@Sushree:~/Desktop/opensourcetutorial$ ls
hello.txt welcome.txt
To create multiple files at a time, specify space separated names of the files
sushree@Sushree:~/Desktop/opensourcetutorial$ ls
hello.txt welcome.txt
sushree@Sushree:~/Desktop/opensourcetutorial$ touch test.txt test1.txt test2.txtsushree@Sushree:~/Desktop/opensourcetutorial$ ls
hello.txt test1.txt test2.txt test.txt welcome.txt
To create multiple files with a variety of patterns
sushree@Sushree:~/Desktop/opensourcetutorial$ touch {a..c}.txt
sushree@Sushree:~/Desktop/opensourcetutorial$ ls
a.txt b.txt c.txt hello.txt test1.txt test2.txt test.txt welcome.txt
To change the access time
sushree@Sushree:~/Desktop/opensourcetutorial$ stat a.txt
File: ‘a.txt’
Size: 0 Blocks: 0 IO Block: 4096 regular empty file
Device: 809h/2057d Inode: 2121285 Links: 1
Access: (0664/-rw-rw-r--) Uid: ( 1000/ sushree) Gid: ( 1000/ sushree)
Access: 2019-03-31 18:27:02.261105369 +0530
Modify: 2019-03-31 18:27:02.261105369 +0530
Change: 2019-03-31 18:27:02.261105369 +0530
Birth: -
sushree@Sushree:~/Desktop/opensourcetutorial$ touch -a a.txt
sushree@Sushree:~/Desktop/opensourcetutorial$ stat a.txt
File: ‘a.txt’
Size: 0 Blocks: 0 IO Block: 4096 regular empty file
Device: 809h/2057d Inode: 2121285 Links: 1
Access: (0664/-rw-rw-r--) Uid: ( 1000/ sushree) Gid: ( 1000/ sushree)
Access: 2019-03-31 18:33:50.857102355 +0530
Modify: 2019-03-31 18:27:02.261105369 +0530
Change: 2019-03-31 18:33:50.857102355 +0530
Birth: -
Note : the access time changes from 18:27 to 18:33 whereas the modified time still remains the same.
To change the last modified time
sushree@Sushree:~/Desktop/opensourcetutorial$ stat a.txt
File: ‘a.txt’
Size: 0 Blocks: 0 IO Block: 4096 regular empty file
Device: 809h/2057d Inode: 2121285 Links: 1
Access: (0664/-rw-rw-r--) Uid: ( 1000/ sushree) Gid: ( 1000/ sushree)
Access: 2019-03-31 18:33:50.857102355 +0530
Modify: 2019-03-31 18:27:02.261105369 +0530
Change: 2019-03-31 18:33:50.857102355 +0530
Birth: -
sushree@Sushree:~/Desktop/opensourcetutorial$ touch -m a.txt
sushree@Sushree:~/Desktop/opensourcetutorial$ stat a.txt
File: ‘a.txt’
Size: 0 Blocks: 0 IO Block: 4096 regular empty file
Device: 809h/2057d Inode: 2121285 Links: 1
Access: (0664/-rw-rw-r--) Uid: ( 1000/ sushree) Gid: ( 1000/ sushree)
Access: 2019-03-31 18:33:50.857102355 +0530
Modify: 2019-03-31 18:34:09.045102221 +0530
Change: 2019-03-31 18:34:09.045102221 +0530
Birth: -
Note : the modified time changes from 18:27 to 18:34
To change both the access time as well as the modified time
sushree@Sushree:~/Desktop/opensourcetutorial$ stat a.txt
File: ‘a.txt’
Size: 0 Blocks: 0 IO Block: 4096 regular empty file
Device: 809h/2057d Inode: 2121285 Links: 1
Access: (0664/-rw-rw-r--) Uid: ( 1000/ sushree) Gid: ( 1000/ sushree)
Access: 2019-03-31 18:33:50.857102355 +0530
Modify: 2019-03-31 18:34:09.045102221 +0530
Change: 2019-03-31 18:34:09.045102221 +0530
Birth: -
sushree@Sushree:~/Desktop/opensourcetutorial$ touch -am a.txt
sushree@Sushree:~/Desktop/opensourcetutorial$ stat a.txt
File: ‘a.txt’
Size: 0 Blocks: 0 IO Block: 4096 regular empty file
Device: 809h/2057d Inode: 2121285 Links: 1
Access: (0664/-rw-rw-r--) Uid: ( 1000/ sushree) Gid: ( 1000/ sushree)
Access: 2019-03-31 18:43:52.241097918 +0530
Modify: 2019-03-31 18:43:52.241097918 +0530
Change: 2019-03-31 18:43:52.241097918 +0530
Birth: -