I have a list of "tasks" which I go through to learn the shell-code, I need to use grep to isolate the line in /etc/passwd that contains “ubu”. I know that the command less /etc/passwd is used to access /etc/passwd, and that grep is used to find/search for a certain string pattern, but that's about it


With grep:

$ grep -F "ubu" /etc/passwd

This uses grep -F to search for the literal string ubu in the file /etc/passwd. Without the -F, grep would treat ubu as a regular expression. In this case it wouldn't make a difference, but if the string contained characters, like *, which is "special" in regular expressions, then this is how you could make them "less special".

grep will return all lines that contains the match.

If ubu is a username (a complete username, not just a part of one), then the following will additionally do a lookup in any directory service (like LDAP or NIS/YP) that the system may be using:

$ getent passwd ubu
  • Also if I want to search for a string in the /home directory,can I do it the same way? or is there anything else to it? – Ahmad Khateeb May 24 '17 at 6:41
  • @AhmadKhateeb In all files under /home? Try find /home -type f -exec grep -HF "ubu" {} + (see the manual for grep for the -H flag). – Kusalananda May 24 '17 at 6:45
  • @AhmadKahateeb You have to use find here because you are searching in a directory and not in a single file or in a small set of files that you can list on the command line. – Kusalananda May 24 '17 at 6:53
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    Or see if your grep supports the -r option for recursive search (FreeBSD and GNU grep do) – Philippos May 24 '17 at 7:51
  • @Philippos Yes, I don't know why I didn't think about that... – Kusalananda May 24 '17 at 7:52

You should probably start with a tutorial to learn the basics.

If you simply looked for grep's man page, you would have been able to figure it out quite easily.

You can basically do grep "ubu" /etc/passwd.

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