Unix Interview Questions – Part 2

List the files in current directory sorted by size ?
  • ls -l | grep ^- | sort -nr
List the hidden files in current directory ?
  • ls -a1 | grep “^\.”
Delete blank lines in a file ?
  • cat sample.txt | grep -v ‘^$’ > new_sample.txt
What command used to search for a string in particular files ?
  • grep <string_to_search> <Filenames>
Command to display the newly appending lines of a file during appendingdata to the same file by some processes ?
  • tail -f
Change to a directory, which is having very long name ?
  • cd CDMA_3X_GEN*
  • Here original directory name is . .CDMA_3X_GENERATION_DATA..
Display the all files recursively with path under current directory ?
  • find . -depth -print
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.
Display the processes, which are running under yourusername ?
  • ps -aef | grep <username>
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.
Display the files in the directory by file size ?
  • ls -ltr | sort -nr -k 5
How to save man pages to a file ?
  • man <command> | col -b > <output-file>
  • Example : man top | col -b > top_help.txt
How to get the Unix system time?
  • date
How do you find out drive statistics?
  • iostat -E
How to create null file ?
  • cat /dev/null > filename1
Access common commands quicker ?
  • ps -ef | grep -i $@
Display the page size of memory ?
  • pagesize -a
Display Ethernet Address arp table ?
  • arp -a
Display the no.of active established connections to localhost ?
  • netstat -a | grep EST
Display the state of interfaces used for TCP/IP traffice ?
  • netstat -i
Display the parent/child tree of a process ?
  • ptree <pid> Example: ptree 1267
  • pstree in linux
Show the working directory of a process ?
  • pwdx <pid> Example: pwdx 1267
Display the processes current open files ?
  • pfiles <pid> Example: pfiles 1267
Display the inter-process communication facility status ?
  • ipcs
Display the top most process utilizing most CPU ?
  • top
Alternative for top command ?
  • prstat -a
Explain iostat, vmstat and netstat.
  • Iostat reports on terminal, disk and tape I/O activity.
  • Vmstat reports on virtual memory statistics for processes, disk, tape and CPU activity.
  • Netstat reports on the contents of network data structures.


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