Sunday, 2 March 2014


Unix/Linux Command 



File Commands

1. ls -                                         Directory listing
2. ls -al -                                    Formatted listing with hidden files
3. ls -lt -                                     Sorting the Formatted listing by time modification
4. cd dir -                                  Change directory to dir
5. cd -                                       Change to home directory
6. pwd -                                    Show current working directory
7. mkdir dir -                              Creating a directory dir
8. cat >file -                               Places the standard input into the file
9. more file-                              Output the contents of the file
10. head file-                             Output the first 10 lines of the file
11. tail file -                               Output the last 10 lines of the file
12. tail -f file-                            Output the contents of file as it grows,starting with
                                                  the last 10 lines
13. touch file -                           Create or update file
14. rm file -                                Deleting the file
15. rm -r dir                               Deleting the directory
16. rm -f file                               Force to remove the file
17. rm -rf dir                              Force to remove the directory dir
18. cp file1 file2                         Copy the contents of file1 to file2
19. cp -r dir1 dir2                      Copy dir1 to dir2;create dir2 if not present
20. mv file1 file2                        Rename or move file1 to file2,if file2 is an existing
21. ln -s file link                         Create symbolic link link to file

Process management

1. ps -                                      To display the currently working processes
2. top -                                     Display all running process
3. kill pid -                                Kill the process with given pid
4. killall proc -                          Kill all the process named proc
5. pkill pattern -                        Will kill all processes matching the pattern
6. bg -                                      List stopped or background jobs,resume a stopped
                                                job in the background
7. fg -                                       Brings the most recent job to foreground
8. fg n -                                    Brings job n to the foreground

File permission

1. 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)


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

1. date -                                    Show the current date and time
2. cal -                                      Show this month's calender
3. uptime-                                 Show current uptime
4. w -                                       Display who is on line
5. whoami-                               Who you are logged in as
6. finger user-                           Display information about user
7. uname -a                              Show kernel information
8. cat /proc/cpuinfo -                 Cpu information
9. cat proc/meminfo-                 Memory information
10. man command-                  Show the manual for command
11. df -                                    Show the disk usage
12. du-                                    Show directory space usage
13. free-                                  Show memory and swap usage
14. whereis app-                      Show possible locations of app
15. which app -                       Show which applications will be run by default


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


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


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

You can found more info in the below links