CODEWITHSUNDEEP
linuxstringbashshellgrep
Yahya Yahyaoui
Yahya Yahyaoui

Reputation: 2953

Linux Check if string exists as separate word (not as substring of another)

I have a file that contains strings, and I would like to check if a string exists in that file as a separate word. example:

string = rambox

"grep" command will tell that "rambox" exists

"grep" command will tell that "rambox" exists coz it exists as a substring of the path "initrd=yahya/rambox/initramfs11.cpio.gz" and this is not correct. I want to obtain that "rambox" doesn't exist in the second example. Is there a way ?

Upvotes: 0

Views: 137

Answers (3)

vlp
vlp

Reputation: 603

even the answer from Maroun Maroun sims right I would change space by this regexp [[:space:]] which will cover all free space like for example tab

input file

# cat testfile
rambox test test
testrambox test test
test test rambox        with tab
test test rambox
test testrambox
#

output:

# grep -P '(^|[[:space:]])rambox($|[[:space:]])' testfile
rambox test test
test test rambox        with tab
test test rambox
#

Upvotes: 1

bishop
bishop

Reputation: 39374

Sounds like you want "rambox" to be surrounded by any amount of white-space or at the beginning or ending of the line. \b and other word boundary solutions (eg, grep -w) won't work here, because / counts as a non-word.

You could write your own interpretation of "word boundary", but in this simple case it's not really worth it.

For this case, I'd probably just manually handle the beginning of line and end of line scenarios: 

$ cat -vet junk
rambox$
 rambox$
rambox $
 rambox$
 foo rambox bar$
 foo  rambox bar$
/rambox/$
ramboxfoo$
ramboxfoo $
 foorambox$
 foorambox $

$ egrep '(^\s*rambox\s+|\s+rambox\s+|\s+rambox\s*$)' junk
 rambox
rambox
 rambox
 foo rambox bar
 foo  rambox bar

Upvotes: 1

Maroun
Maroun

Reputation: 95958

You can use grep with the -P flag:

grep -P '^rambox | rambox$| rambox '

Or even better:

grep -P '(^| )rambox($| )'
  • ^ matches beginning of line
  • $ matches end of line
  • | is OR regex
  • -P, --perl-regexp PATTERN is a Perl regular expression

Upvotes: 3

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