Linux - Blog -Basic - Commands & Functionals

Linux - Commands - Made Easy

 Unix/Linux Command

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 --->  Creating a directory.
•  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 
• the last 10 lines
•  touch filename  ----> Create or update file.
•  rm filename       ----> 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 existing directory.
• 
  
•  ln -s   --->  file link Create symbolic link link to file.

Process management - Linux Commands

•  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 - Linux - Commands

•  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 Commands - Linux

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

System Info - Linux-commands

•  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
•  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 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- Linux- Commands

• 1. tar cf file.tar file Create tar named file.tar containing file
• 2. tar xf file.tar Extract the files from file.tar
• 3. tar czf file.tar.gz files Create a tar with Gzip compression
• 4. tar xzf file.tar.gz Extract a tar using Gzip
• 5. tar cjf file.tar.bz2 Create tar with Bzip2 compression
• 6. tar xjf file.tar.bz2 Extract a tar using Bzip2
• 7. gzip file Compresses file and renames it to file.gz
• 8. gzip -d file.gz Decompresses file.gz back to file.

Network- Commands

• 1. ping host Ping host and output results
• 2. whois domain Get whois information for domains
• 3. dig domain Get DNS information for domain
• 4. dig -x host Reverse lookup host
• 5. wget file Download file
• 6. wget -c file Continue a stopped download

Unix/Linux Command Reference Shortcuts

• 1. ctrl+c Halts the current command
• 2. ctrl+z Stops the current command, resume with fg in the 
• foreground or bg in the background
• 3. ctrl+d Logout the current session, similar to exit 
• 4. ctrl+w Erases one word in the current line
• 5. ctrl+u Erases the whole line
• 6. ctrl+r Type to bring up a recent command
• 7. !! Repeats the last command
• 8. exit Logout the current session.