Unix/Linux Commands

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 directory
21. ln -s file link --> Create symbolic link link to file

Process management1. ps --> To display the currently working processes
2. top --> Display all running process Unix/Linux Command Reference
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 permission1. 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)
 

Searching1. 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 Info1. 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
Unix/Linux --> Command Reference
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
 

Compression1. 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
 

Network1. 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
 

Shortcuts1. 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 Unix/Linux Command Reference