1. List the files in current directory sorted by size ? – ls -l | grep ^- | sort -nr
  2. List the hidden files in current directory ? – ls -a1 | grep “^.”
  3. Delete blank lines in a file ? – cat sample.txt | grep -v ‘^$’ > new_sample.txt
  4. Search for a sample string in particular files ? – grep “Debug” *.confHere grep uses the string “Debug” to search in all files with extension“.conf” under current directory.
  5. Display the last newly appending lines of a file during appendingdata to the same file by some processes ? – tail –f Debug.logHere tail shows the newly appended data into Debug.log by some processes/user.
  6. Display the Disk Usage of file sizes under each directory in currentDirectory ? – du -k * | sort –nr (or) du –k . | sort -nr
  7. Change to a directory, which is having very long name ? – cd CDMA_3X_GEN*Here original directory name is – “CDMA_3X_GENERATION_DATA”.
  8. Display the all files recursively with path under current directory ? – find . -depth -print
  9. Set the Display automatically for the current new user ? – export DISPLAY=eval ‘who am i | cut -d"(" -f2 | cut -d")" -f1′Here in above command, see single quote, double quote, grave ascent is used. Observe carefully.
  10. Display the processes, which are running under yourusername ? – ps –aef | grep MaheshvjHere, Maheshvj is the username.
  11. List some Hot Keys for bash shell ? – Ctrl+l – Clears the Screen. Ctrl+r – Does a search in previously given commands in shell. Ctrl+u – Clears the typing before the hotkey. Ctrl+a – Places cursor at the beginning of the command at shell. Ctrl+e – Places cursor at the end of the command at shell. Ctrl+d – Kills the shell. Ctrl+z – Places the currently running process into background.
  12.  Display the files in the directory by file size ? – ls –ltr | sort –nr –k 5
  13. How to save man pages to a file ? – man <command> | col –b > <output-file>Example : man top | col –b > top_help.txt
  14. How to know the date & time for – when script is executed ? – Add the following script line in shell script.eval echo “Script is executed at date” >> timeinfo.infHere, “timeinfo.inf” contains date & time details ie., when script is executed and history related to execution.
  15. How do you find out drive statistics ? – iostat -E
  16. Display disk usage in Kilobytes ? – du -k
  17. Display top ten largest files/directories ? – du -sk * | sort -nr | head
  18. How much space is used for users in kilobytes ? – quot -af
  19. How to create null file ? – cat /dev/null > filename1
  20. Access common commands quicker ? – ps -ef | grep -i $@
  21. Display the page size of memory ? – pagesize -a
  22. Display Ethernet Address arp table ? – arp -a
  23. Display the no.of active established connections to localhost ? – netstat -a | grep EST
  24. Display the state of interfaces used for TCP/IP traffice ? – netstat -i
  25. Display the parent/child tree of a process ? – ptree <pid> Example: ptree 1267
  26. Show the working directory of a process ? – pwdx <pid> Example: pwdx 1267
  27. Display the processes current open files ? – pfiles <pid> Example: pfiles 1267
  28. Display the inter-process communication facility status ? – ipcs
  29. Display the top most process utilizing most CPU ? – top –b 1
  30. Alternative for top command ? – prstat –a