Here’s a quick overview of commands:
ls– lists a directory’s content.
pwd– shows the current working directory’s path.
cd– changes the working directory.
mkdir– creates a new directory.
rmdir– removes a folder or path.
rm– deletes a file.
cp– copies files and directories, including their content.
mv– moves or renames files and directories.
touch– creates a new empty file.
file– checks a file’s type.
zip and unzip– create and extracts a ZIP archive.
tar– archives files without compression in a TAR format.
nano, vi, and jed– edits a file with a text editor.
cat– lists, combines, and writes a file’s content as a standard output.
grep– searches a string within a file.
sed– finds, replaces, or deletes patterns in a file.
head– displays a file’s first ten lines.
tail– prints a file’s last ten lines.
awk – finds and manipulates patterns in a file.
sort – reorders a file’s content.
cut – sections and prints lines from a file.
diff – compares two files’ content and their differences.
tee – prints command outputs in Terminal and a file.
locate – finds files in a system’s database.
find – outputs a file or folder’s location.
sudo – runs a command as a superuser.
su – runs programs in the current shell as another user.
Chmod – modifies a file’s read, write, and execute permissions.
Chown – changes a file, directory, or symbolic link’s ownership.
useradd and userdel – creates and removes a user account.
df – displays the system’s overall disk space usage.
du – checks a file or directory’s storage consumption.
top – displays running processes and the system’s resource usage.
htop – works like top but with an interactive user interface.
ps – creates a snapshot of all running processes.
50 Linux Commands everyone should know to clear the Interview
uname – prints information about your machine’s kernel, name, and hardware.
hostname – shows your system’s hostname.
time – calculates commands’ execution time.
systemctl – manages system services.
watch – runs another command continuously.
jobs – displays a shell’s running processes with their statuses.
kill – terminates a running process.
shutdown – turns off or restarts the system.
ping – checks the system’s network connectivity.
wget – downloads files from a URL.
curl – transmits data between servers using URLs.
scp – securely copies files or directories to another system.
rsync – synchronizes content between directories or machines.
Ifconfig – displays the system’s network interfaces and their configurations.
netstat – shows the system’s network information, like routing and sockets.
traceroute – tracks a packet’s hops to its destination.
nslookup – queries a domain’s IP address and vice versa. Nslookup is used for handling
DNS lookups and displays crucial information such as MX records, and the IP address
associated with a domain name
dig – displays DNS information, including record types.
history – lists previously run commands.
man – shows a command’s manual.
echo – prints a message as a standard output.
ln – links files or directories.
alias and unalias – sets and removes an alias for a file or command.
Cal – displays a calendar in Terminal.
apt-get – manages Debian-based distros package libraries.
who: The ‘$ who’ command displays all the users who have logged into the system currently.
pwd : The ‘$pwd’ command stands for ‘Present working directory’ and as the name says, it displays the directory in which we are currently.
cd : The ‘$ cd’ command stands for ‘change directory’
touch : The ‘$ touch’ command creates a file
cp : This ‘$ cp ‘command stands for ‘copy’ and it simply copy/paste the file wherever you want to
Chmod : The ‘$ Chmod’ command stands for change mode command. As there are many modes in Unix that can be used to manipulate files in the Unix environment. Basically, there are 3 modes that we can use with the ‘Chmod’ command
1. +w (stands for write and it changes file permissions to write)
2. +r (stands for read and it changes file permissions to read)
3. +x (generally it is used to make a file executable)
default permissions of file and folder in Linux: – rw-rw-r–
Click here to know How to make money from Facebook
Q. What are the default permissions in Linux?
A. Linux uses the following default mask and permission values:
The system default permission values are 777 (rwxrwxrwx) for folders and 666 (rw-rw-rw-) for files. The default mask for a non-root user is 002, changing the folder permissions to 775 (rwxrwxr-x), and file permissions to 664 (rw-rw-r–).
Cal : The ‘$ Cal’ means calendar and it simply display calendar on to your screen.
sort : As the name suggests the ‘$ sort’ sorts the contents of the file according to the ASCII rules.
grep : grep is an acronym for ‘globally search a regular expression and print it’. The ‘$ grep’ command searches the specified input fully(globally) for a match with the supplied pattern and displays it
lpr: The ‘$ lpr’ command send a file to the printer for printing.
passwd : The ‘$ passwd’ command simply changes the password of the user.
Q. What is SSH used for in Linux?
A. The ssh command provides a secure encrypted connection between two hosts over an insecure network in Linux
Click here to know How to Make money in your free time
Some more commands are:-
Command | Description |
Ls | Lists all files and directories in the present working directory |
ls – R | Lists files in sub-directories as well |
ls – a | Lists hidden files as well |
ls – al | Lists files and directories with detailed information like permissions, size, owner, etc. |
cat > filename | Creates a new file |
cat filename | Displays the file content |
cat file1 file2 > file3 | Joins two files (file1, file2) and stores the output in a new file (file3) |
mv file “new file path” | Moves the files to the new location |
mv filename new_file_name | Renames the file to a new filename |
sudo | Allows regular users to run programs with the security privileges of the superuser or root |
rm filename | Deletes a file |
man | Gives help information on a command |
history | Gives a list of all past basic Linux commands list typed in the current terminal session |
clear | Clears the terminal |
mkdir directory name | Creates a new directory in the present working directory or a at the specified path |
rmdir | Deletes a directory |
mv | Renames a directory |
pr -x | Divides the file into x columns |
pr -h | Assigns a header to the file |
pr -n | Denotes the file with Line Numbers |
lp -nc lpr c | Prints “c” copies of the File |
lp -d lpr -P | Specifies name of the printer |
apt-get | Command used to install and update packages |
mail -s ‘subject’ -c ‘cc-address’ -b ‘bcc-address’ ‘to-address’ | Command to send email |
mail -s “Subject” to-address < Filename | Command to send email with attachment |
Linux commands helped me a lot during interview.