Top Linux Commands

#Linux Online Compiler

1. https://www.tutorialspoint.com/linux_terminal_online.php
2. https://bellard.org/jslinux/vm.html?url=alpine-x86.cfg&mem=192

File Commands:

• ls – directory listing
• ls -al – formatted listing with hidden files
• cd dir - change directory to dir
• cd – change to home
• pwd – show current directory
• mkdir dir – create a directory dir
• rm file – delete file
• rm -r dir – delete directory dir
• rm -f file – force remove file
• rm -rf dir – force remove directory dir *
• cp file1 file2 – copy file1 to file2
• cp -r dir1 dir2 – copy dir1 to dir2; create dir2 if it doesn't exist
• mv file1 file2 – rename or move file1 to file2 if file2 is an existing directory, moves file1 into directory file2
• ln -s file link – create symbolic link link to file
• touch file – create or update file
• cat > file – places standard input into file
• more file – output the contents of file
• head file – output the first 10 lines of file
• tail file – output the last 10 lines of file
• tail -f file – output the contents of file as it grows, starting with the last 10 lines

#Process Management Commands:

• ps – display your currently active processes
• top – display all running processes
• kill pid – kill process id pid
• killall proc – kill all processes named proc *
• bg – lists stopped or background jobs; resume a stopped job in the background
• fg – brings the most recent job to foreground
• fg n – brings job n to the foreground

#File Permissions Commands:

• chmod octal file – change the permissions of file to octal, which can be found separately for user, group, and world by adding:
• 4 – read (r)
• 2 – write (w)
• 1 – execute (x)

#Examples:

• chmod 777 – read, write, execute for all
• chmod 755 – rwx for owner, rx for group and world

#SSH Commands:

• ssh user@host – connect to host as user
• ssh -p port user@host – connect to host on port port as user
• ssh-copy-id user@host – add your key to host for user to enable a keyed or passwordless login

#Searching Commands:

• grep pattern files – search for pattern in files
• 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

#System Info Commands:

• date – show the current date and time
• cal – show this month's calendar
• uptime – show current uptime
• w – display who is online
• whoami – who you are logged in as
• finger user – display information about user
• uname -a – show kernel information
• cat /proc/cpuinfo – cpu information
• cat /proc/meminfo – memory information
• man command – show the manual for command
• df – show disk usage
• du – show directory space usage
• free – show memory and swap usage
• whereis app – show possible locations of app
• which app – show which app will be run by default

#Compression Commands:

• tar cf file.tar files – create a tar named file.tar containing files
• tar xf file.tar – extract the files from file.tar
• tar czf file.tar.gz files – create a tar with Gzip compression
• tar xzf file.tar.gz – extract a tar using Gzip
• tar cjf file.tar.bz2 – create a tar with Bzip2 compression
• tar xjf file.tar.bz2 – extract a tar using Bzip2
• gzip file – compresses file and renames it to file.gz
• gzip -d file.gz – decompresses file.gz back to file

#Networking Commands:

• ping host – ping host and output results
• whois domain – get whois information for domain
• dig domain – get DNS information for domain
• dig -x host – reverse lookup host
• wget file – download file
• wget -c file – continue a stopped download

##Installation Commands:

• dpkg -i pkg.deb – install a package (Debian)
• rpm -Uvh pkg.rpm – install a package (RPM)

#Install from source:

• ./configure
• make
• make install

#Shortcuts:

• Ctrl+C – halts the current command
• Ctrl+Z – stops the current command, resume with
• fg in the foreground or bg in the background
• Ctrl+D – log out of current session, similar to exit
• Ctrl+W – erases one word in the current line
• Ctrl+U – erases the whole line
• Ctrl+R – type to bring up a recent command
• !! - repeats the last command
• exit – log out of current session