Unix Interview Question and Answers

21. what are the different commands used to create files?
 
  • touch - to create empty files.(e.g) - touch ‹filename›
  • vi ‹filename›
  • cat>filename
.
22. What is chmod, chown and chgrp?
 
  • Chmod : It is used for to change permissions on files.
  • Chown : It is used for to change ownership of a file.
  • Chgrp : It is used for to change group of the file.
23. What are PIDs?
  They are process IDs given to processes. A PID can vary from 0 to 65535.
24. What does the top command display?
 
  • Top command displays the current ammount of memory occupied by the currently executing processes and the details.
  • In addition to memory usage top command displays cpu usage and process details.
25. What is the command to send message to all users who are logged in?
  Wall
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