How to grep lines which does not begin with "#" or ";"?

Question

I want to grep smb.conf and see only lines which are not commented.

testparm do this better as this display default values too. — F. Hauri - Give Up GitHub, Jan 11 '13 at 20:08
@F.Hauri Thank you. it is working as well. But it is also produce some unneeded (in my case) information, which should be grepped also... — denys, Jan 11 '13 at 20:21
superset: any regex: http://superuser.com/questions/655715/regex-does-not-begin-by-pattern — Ciro Santilli OurBigBook.com, Jul 27 '15 at 07:33
Another way through PCRE grep https://stackoverflow.com/a/45917459/3297613 — Avinash Raj, Aug 28 '17 at 11:03

score 223 · Accepted Answer · edited Mar 16 '17 at 10:36

223

grep "^[^#;]" smb.conf

The first ^ refers to the beginning of the line, so lines with comments starting after the first character will not be excluded. [^#;] means any character which is not # or ;.

In other words, it reports lines that start with any character other than # and ;. It's not the same as reporting the lines that don't start with # and ; (for which you'd use grep -v '^[#;]') in that it also excludes empty lines, but that's probably preferable in this case as I doubt you care about empty lines.

If you wanted to ignore leading blank characters, you could change it to:

grep '^[[:blank:]]*[^[:blank:]#;]' smb.conf

or

grep -vxE '[[:blank:]]*([#;].*)?' smb.conf

Or

awk '$1 ~ /^[^;#]/' smb.conf

edited Mar 16 '17 at 10:36

Stéphane Chazelas

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answered Jan 11 '13 at 20:05

goldilocks

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right answer is: cat /etc/samba/smb.conf | grep ^[^#\;] But anyway Thank you – denys Jan 11 '13 at 20:09
Yeah, or you could use "quotes"; I edited that in subsequently. – goldilocks Jan 11 '13 at 20:11
or with quotes - as you just corrected :) – denys Jan 11 '13 at 20:11
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@denys You're wrong: goldilocks's response in not worst than your. .1 Please avoid using cat ...| syntax!. .2 For whipping empty lines AND lines containing only space, maybe with comments U could use this: grep -v "^ *$#.*\|$$" < smb.conf – F. Hauri - Give Up GitHub Jan 11 '13 at 20:14
@denys For samba, did you try testparm command? – F. Hauri - Give Up GitHub Jan 11 '13 at 20:15
@F.Hauri: What's wrong with cat ... |? – Emanuel Berg Jan 11 '13 at 21:51
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@EmanuelBerg It's an useless fork. cat file | grep "blah" implie running two binaries through a fifo, while grep "blah" <file do exactly same and bind file naturaly to grep's STDIN . [bash] useless cat is a full featured subject of search through any search engine! -> http://blog.sanctum.geek.nz/useless-use-of-cat/ ... for sample – F. Hauri - Give Up GitHub Jan 11 '13 at 22:01
@F.Hauri: If it does exactly the same, how can it be useless? – Emanuel Berg Jan 11 '13 at 22:08
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It doesn't do exactly the same. It creates 2 processes and a pipe where 1 process is enough. Read the link given in @F.Hauri's last comment. – rahmu Jan 11 '13 at 22:12
@rahmu: Do you habitually run out of processes? That syntax is intuitive and there is nothing wrong using it. – Emanuel Berg Jan 12 '13 at 00:02
@EmanuelBerg If you use it, you will be attacked by a velociraptor. On a more serious note, you can use the <filename command syntax which has the merits of both; you don't use cat and you get the filename before the command. – wizzwizz4 Mar 19 '17 at 22:04
"Useless use of cat" is not intuitive -- I used to do it a lot. It's habitual. People new to the command line who learn to use grep correctly will not find it "counter-intuitive" vs. useless use of cat but, I think, more likely vice versa, because the issue is a pretty drop dead simple one to understand. There is no possible advantage to useless use of cat unless you've become habituated to doing it (i.e., you have a bad habit!). – goldilocks Mar 22 '17 at 12:22
I did a similar thing to look for lines not starting with a quote, but '^[^"]' found the first line of the file, which did start with a quote! Does ^ only work if there is a previous line? – Michael Jan 19 '22 at 18:00

score 5 · Answer 2 · edited Mar 16 '17 at 10:49

These examples might be of use to people.

[user@host tmp]$ cat whitespacetest
# Line 1 is a comment with hash symbol as first char

# Line 2 is a comment with hash symbol as second char
  # Line 3 is a comment with hash symbol as third char
        # Line 4 is a comment with tab first, then hash
        ; Line 5 is a comment with tab first, then semicolon. Comment char is ;
; Line 6 is a comment with semicolon symbol as first char
[user@host tmp]$

The first grep example excludes lines beginning with any amount of whitespace followed by a hash symbol.

[user@host tmp]$ grep -v '^[[:space:]]*#' whitespacetest

        ; Line 5 is a comment with tab first, then semicolon. Comment char is ;
; Line 6 is a comment with semicolon symbol as first char
[user@host tmp]$

The second excludes lines beginning with any amount of whitespace followed by a hash symbol or semicolon.

[user@host tmp]$ grep -v '^[[:space:]]*[#;]' whitespacetest

[user@host tmp]$

score 5 · Answer 3 · edited Mar 16 '17 at 10:38

5

The pipe to grep in oliver nadj's answer may be eliminated by (assuming GNU grep or compatible):

grep -v "^\s*[#\;]\|^\s*$" <some_conf_file>

edited Mar 16 '17 at 10:38

Stéphane Chazelas

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answered Oct 13 '15 at 08:43

Morten Lind

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Second grep i@nadj's looks useless , @goldilocks's answer was more than eough. – Archemar Oct 13 '15 at 09:19
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I agree that goldilocks's answer was correct. However, I also considered it useful to not show empty lines. – Morten Lind Oct 13 '15 at 17:41

score 5 · Answer 4 · answered Dec 21 '15 at 23:55

5

Vim solution:

:v/^\s*[#\n]/p

I stumbled across this question when trying to find the vim solution myself.

answered Dec 21 '15 at 23:55

David Lord

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This would also delete lines that starts with blanks. – Kusalananda Jun 07 '19 at 14:57
True. I found that useful for config files as lines between comments otherwise fill up the output. If you'd rather keep the blank lines, change the * to + like so: v/^\s+[#\n]/p – David Lord Jun 08 '19 at 23:27

score 3 · Answer 5 · edited Mar 19 '15 at 03:20

3

grep -v "^\s*[#;]" any.conf | grep -v "^\s*$"

that is what works for me. ignore commented or empty lines, even whitespace before hash mark or semicolon

edited Mar 19 '15 at 03:20

muru

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answered Mar 19 '15 at 03:10

oliver nadj

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score 0 · Answer 6 · edited Apr 16 '19 at 14:25

0

Here i got better one (assuming GNU grep or compatible):

grep -v '^[#;/%<]\|^\s*$' anyfile.conf

exclude for lines which begins with #;/%< which are in square brackets and the second filter after pipe is \s*$ for blank lines.

edited Apr 16 '19 at 14:25

Rui F Ribeiro

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answered Mar 16 '17 at 09:43

S. Venkata Ramana

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In what type of conf files are < or / used for comments? I know a lot of conf file formats where < is everything but a comment. ! is sometimes used like in X resource files. – Stéphane Chazelas Mar 16 '17 at 10:42

score -1 · Answer 7 · edited May 23 '17 at 12:39

-1

grep -v '^$\|^\s*#' temp

This one's a lot better, I got it from https://stackoverflow.com/questions/17392869/how-to-print-a-file-excluding-comments-and-blank-lines-using-grep-sed

It assumes GNU grep or compatible.

edited May 23 '17 at 12:39

Community

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answered Mar 31 '16 at 04:41

Tek

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The question also considers lines starting with ; as a comment that should be removed. – Kusalananda Jun 07 '19 at 14:56

score -2 · Answer 8 · edited Jul 11 '19 at 18:41

-2

egrep -v "^#|^$" anyfile.txt

this command is to grep all info in file excluding comments and blank lines.

edited Jul 11 '19 at 18:41

Jeff Schaller

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answered Jul 11 '19 at 18:14

Mustafa Hussein

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Notice that smb.conf also comments with ; – Jeff Schaller Jul 11 '19 at 18:41

score -3 · Answer 9 · edited Jun 07 '19 at 12:09

-3

This should display you the file without those lines that begin with #: grep -v "^#" filename

edited Jun 07 '19 at 12:09

Philippos

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answered Jun 07 '19 at 11:21

Avinasha

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This does nothing to lines starting with ;. – Kusalananda Jun 07 '19 at 14:56

How to grep lines which does not begin with "#" or ";"?

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