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
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
26. Show the working directory of a process ? - pwdx
27. Display the processes current open files ? - pfiles
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