Files and Navigating

• ls - directory listing (list all files/folders of dir)
• ls -l - formatted listing
• ls -la - formatted listing including hidden files
• cd dir - change directory to dir
• cd .. - change to parrent directory
• cd ../dir - change directory to parent dir
• cd - change to home directory
• pwd - show current directory
• mkdir dir - create a directory dir
• rm file - delete file
• rm -rf dir - recursive remove directory and content
• rm -rf / - don't do that!
• cp file1 file2 - copy file1 to file2
• mv file1 file2 - move file1 to file2
• touch file - create or update file
• cat file - output content of file
• cat > file - write standard input into file
• cat >> file - append standard input into file
• tail -f file - output content of file as it grows

Networking

• ping target - ping target hostname/ip
• whois domain - get whois for domain
• dig domain - get DNS for domain
• dig -x host - reverse lookup host
• wget file - download file
• wget -c file - continue stopped download
• wget -r url - recursivelly download files from url
• curl url - outputs webpage from url
• curl -o site.html url - write the page to site.html
• ssh use@host - connet to host as user
• ssh -p port user@host - connect using port
• ssh -D user@host - connect and use bind port

Processes

• ps - display currently active processes
• ps aux - detailed outputs
• kill pid - kill process with process id (pid)
• killall proc - kill all processes named proc

System Info

• date - show current date/time
• uptime - show uptime
• whoami - who you're logged in as
• w - display who is online
• cat /proc/cpuinfo - display cpu information
• cat /proc/meminfo - memory information
• free - show memory and swap usage
• du - show directory space usage
• du -sh - display readable sizes in GB
• df - show disk usage
• uname -a - show kernel config

Compressing

• tar cf file.tar files - tar files into file.tar
• tar xf file.tar - untar into current directory
• tar tf file.tar - show content of archive

Options:

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

Permissions

• chmod actual file - change permissions of file

Options:

• 4 - read (r)
• 2 - write (w)
• 1 - execute (x)

order: owner/group/public

chmod 777 = rwx for everyone

chmod 755 = rw for ownerm rx for group and publicly

Some Others

• grep pattern files - search in files for pattern
• grep -r pattern dir - recursive pattern search in dir
• locate file - find all instances of file
• whereis app - show possible locations of app
• man command - show manual page for command