BasicLinuxCommand [Unix/Linux Command Reference]

File Commands

• ls : Directory listing
• ls -al : Formatted listing with hidden files
• ls -lt : Sorting the Formatted listing by time modification
• cd dir : Change directory to dir
• cd Change : to home directory
• pwd : Show current working directory
• mkdir dir : Creating a directory dir
• cat > file : Places the standard input into the file
• more file : Output the contents of the file
• head file : Output the first 10 lines of the file
• tail file : Output the last 10 lines of the file
• tail -f file : Output the contents of file as it grows,starting with last 10 lines
• touch file : Create or update file
• rm file : Deleting the file
• rm -r dir : Deleting the directory
• rm -f file : Force to remove the file
• rm -rf dir : Force to remove the directory dir
• cp file1 file2 : Copy the contents of file1 to file2
• cp -r dir1 dir2 : Copy dir1 to dir2;create dir2 if not present
• mv file1 file2 : Rename or move file1 to file2,if file2 is an existingdirectory
• ln -s file link : Create symbolic link link to file

Process management

• ps : To display the currently working processes
• top : Display all running process
• kill pid : Kill the process with given pid
• killall proc : Kill all the process named proc
• pkill pattern : Will kill all processes matching the pattern
• bg : List 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 permission

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

Searching

• grep pattern file : Search for pattern in file
• grep -r pattern dir : Search recursively for pattern in dir
• command | grep pattern : Search pattern in the output of a command
• locate file : Find all instances of file
• find .-name filename Searches in the current directory (represented by a period) and below it, for files and directories with names starting with filename
• pgrep pattern : Searches for all the named processes , that matches with the pattern and, by default, returns their ID

System Info

• date : Show the current date and time
• cal : Show this month's calender
• uptime :Show current uptime
• w : Display who is on line
• whoami : Who you are logged in as Unix/Linux Command Reference
• finger user : Display information about user
• uname -a : Show kernel information
• cat /proc/cpuinfo : show Cpu information
• cat proc/meminfo : show Memory information
• man command : Show the manual for command
• df : Show the disk usage
• du : Show directory space usage
• free : Show memory and swap usage
• whereis app : Show possible locations of app
• which app : Show which applications will be run by default

Compression

• tar cf file.tar file : Create tar named file.tar containing file
• 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 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

Network

• ping host : Ping host and output results
• whois domain : Get whois information for domains
• dig domain : Get DNS information for domain
• dig -x host : Reverse lookup host
• wget file : Download file
• wget -c file: Continue a stopped download
• netstat : displays various network related information such as network connections, routing tables, interface statistics, masquerade connections, ...
• nslookup : used to obtain information about Internet servers. As its name suggests, the utility finds name server information for domains by querying DNS

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 Logout the 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 : Logout the current session