Ultimate Guide to Basic Linux Commands

Linux Commands

Linux Commands

Linux is a free, most-used and open-source operating system based on the Linux kernel. First released in 199o’s by Linus Torvalds. Approximately 90% of the internet is powered by Linux servers. Basically, Linux command should run on a shell/Terminal. Shell is a program that receives commands from the user and gives it to the OS for processing and returns the output.

Learning Linux commands for managing systems can give you more speed and control over your workflow. Here is some Basic Linux commands for beginners.

Basic Linux Commands

  • File Command: The file command determine how to view and working with linux files
ls - directory listing
ls -al -formatted listing with hidden files
ls -lh - list directory with readable file size
cd dir - change directory to dir
cd - change to home
pwd - show current directory/print working directory
mkdir dir - create directory dir
rm file - delete file
rm -r dir - delete directory dir
rm -f file - force remove file
rm -rf dir - remove directory dir
cp file0 file1 - copy file0 to file1
mv file0 file1 - rename file0 to file1
ln -s file link - create symbolic link 'link' to file
touch file - create or update file
cat > file - place standard input into file
more file - output the content of the file
less file - output the content of the file
head file - output first 10 line of file
tail file - output last 10 line of file
tail -f file - output contents of file as it grows
  • System Information: The system information command help you to view linux system information
date - show current datetime
cal - show this month's calender
uptime - show uptime since last reboot
w - display who is online
whoami - who are you logged in as
uname -a - show kernel configuration
cat /proc/cpuinfo - show cpu information
cat /proc/meminfo - show memory information
man command - show manual for command
df - show disk usages
du - show directory space usages
du -sh - human readable size in GB
free - show memory and swap usages
whereis app - show possiable locations of app
which app - show which app will be run by default
  • Searching: The searching command help you to search files on linux system
grep pattern file - search for pattern in file
grep -r pattern dir - search recursively for pattern in dir
command | grep pattern - search for pattern in the output of command
locate file - find all instances of file
grep -Ril 'dir' -e "text" - search text in all files in directory dir
  • Process Management: The process management command help you to managing process of a linux system
ps - display currently active processes
ps aux - ps with more details
kill pid - kill process with pid 'pid'
killall proc - kill all processes named proc
bg - lists stopped/background jobs, resume stopped job in the background
fg - brings most recent job to foreground
fg n - brings job n to foreground
  • File permission: The file permission command help you to setting files permission and ownership on linux system
chmod octal file - change permission of file
chmod -R octal dir - changes permission of all fies in dir

4 – read(r)
2 – write(w)
1– execute(x)

Order: owner/group/world
eg chmod 777 – rwx for everyone
chmod 755 – rw for owner, rx for group/world

  • Compression: The compression command help you to compress files using compression technique on linux system to save disk space.
tar cf file.tar files - tar files into file.tar
tar xf file.tar - untar/extract into current directory
tar tf file.tar - show contents of archive
gzip file - compress fle and rename to file.gz
gzip -d file.gz - decompress file.gz

tar flag:

c- create archive
t – table of contents
x – extract
f – specifile filename
z – use zip/gzip
j – bzip2 compression
k – do not overwrite
T – files from file
w -ask for confirmation
v -verbose

  • Shortcuts

ctrl+c - halts corrent command
ctrl+z - stops current command
fg - resume stopped command in foreground
bg - resume stopped command in background
ctrl+d - logout of current session
ctrl+w - erases one word in current line
ctrl+u - erases whole line
ctrl+r - reverse lookup of previous commands
exit - lohout of current session
  • SSH

ssh [email protected] - connect to host as user on default ssh port
ssh -p port [email protected] - connect using port p
ssh -D port [email protected] - connect and using bind port
ssh -i keyfile [email protected] - connect using ssh key file
  • Installation

./configure
make
make install
  • Network

ping host - ping host 'host'
whois domain - get whois data for domain
dig domain - get DNS information for domain
dig -x host reverse lookup host
wget file_url - download file
wget -c file_url - continue stopped download
wget -r url - recursively download file from url

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