Here are some of the essential linux commands for system administrators and all linux users.
Linux Commands
Below are the top essential linux commands.
Commands to Create Directory & Files in Linux
Create Directory in Linux:
mkdir dirname
Create an empty file on Linux:
touch sample.txt
Create a file on Linux and add some immediate content on it:
cat > sample.txt
How to Delete Files and Directories in the Linux Terminal
To delete a single file:
sudo rm filename
To delete multiple files at once:
sudo rm filename1 filename2 filename3
To remove an empty directory:
sudo rm -d dirname
To remove non-empty directories and all the files within them:
sudo rm -r dirname
To remove multiple directories at once:
rm -r dirname1 dirname2 dirname3
Check File Ownership in Linux
To show who owns a file or what group the file belongs to:
ls -l filename.txt
Change File Ownership Linux
To change the owner and group of a file:
chown USER:GROUP file.txt
Check File Permission in Linux
Check Permissions in Command-Line with Ls Command
ls -l test.txt
It will show you the file permissions and who owns a file or what group the file belongs to.
View file permission in octal notation
stat -c “%a %n” /path/of/file
It will show four things:
File type. There are three possibilities for the type. It can either be a regular file (–), a directory (d) or a link (i).
- File permission of the user (owner)
- File permission of the owner’s group
- File permission of other users
Instead of letters, the octal format represents privileges with numbers:
- r(ead) has the value of 4
- w(rite) has the value of 2
- (e)x(ecute) has the value of 1
- no permission has the value of 0
The privileges are summed up and depicted by one number. Therefore, the possibilities are:
- 7 – for read, write, and execute permission
- 6 – for read and write privileges
- 5 – for read and execute privileges
- 4 – for read privileges
Change File Permission in Linux
Using Chmod Command to Change File Permissions
Sudo chmod [permission] [file_name]
Change permission for all directory/folder under the mentioned DirectoryName
sudo find DIRECTORY -type d -exec chmod 775 {} \;
Change permission for all files under the mentioned DirectoryName
sudo find DIRECTORY -type f -exec chmod 664 {} \;
VIM Editor Commands
To search in vim editor:
Open up your file with vim:
sudo vim myfile.txt
Then press ESC to switch to normal mode and type / followed by the word you are searching for.
NANO Editor Commands
Sudo nano filename
Commands to Check System Information in Linux
Check OS Version Information:
lsb_release -a
Check Disk Space of Linux Instance:
df -h
Check size of a linux directory:
sudo du -sh /var
Check Processor of Linux machine:
cat /proc/cpuinfo
Check RAM of Linux machine:
cat /proc/meminfo
