Difference between revisions of "grep"
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* [[/manpage]] - a nicely-formatted but old version of the grep manpage | * [[/manpage]] - a nicely-formatted but old version of the grep manpage | ||
==Examples== | ==Examples== | ||
| − | ; grep ''text_to_find'' *.log:find ''text_to_find'' by checking all the logfiles in the current folder | + | ; grep ''text_to_find'' *.log:find ''[text_to_find]'' by checking all the logfiles in the current folder |
| − | ; grep -r ''text_to_find'' *:find ''text_to_find'' by checking all files in the current folder or under it | + | ; grep -r ''text_to_find'' *:find ''[text_to_find]'' by checking all files in the current folder or under it |
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| + | Note that you can't do e.g. <code>grep -r ''[text_to_find]'' *.log</code> because that will only search in folders named <code>''[something]''.log</code>. [[/file masks|The reasons for this are complicated.]] | ||
==Questions== | ==Questions== | ||
* So, how do you grep for a string which contains spaces and quote characters? This is probably some standard feature of Linux Shell syntax which everyone knows, but I don't, and that's why this page needs examples. | * So, how do you grep for a string which contains spaces and quote characters? This is probably some standard feature of Linux Shell syntax which everyone knows, but I don't, and that's why this page needs examples. | ||
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*: '''A:''' apparently "*" by itself; see examples above | *: '''A:''' apparently "*" by itself; see examples above | ||
==Notes== | ==Notes== | ||
| − | + | The backtick character ("`") seems to mean "insert the output of this command here" -- so if you're trying to search for a literal backtick, it needs to be escaped with "\" ("\`"). This comes up sometimes when searching for [[SQL]] phrases. | |
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==Links== | ==Links== | ||
* [http://www.gnu.org/software/grep/manual/ official documentation]: more current than the manpage on this server | * [http://www.gnu.org/software/grep/manual/ official documentation]: more current than the manpage on this server | ||
* {{wikipedia}} | * {{wikipedia}} | ||
Latest revision as of 15:13, 21 June 2022
Pages
Examples
- grep text_to_find *.log
- find [text_to_find] by checking all the logfiles in the current folder
- grep -r text_to_find *
- find [text_to_find] by checking all files in the current folder or under it
Note that you can't do e.g. grep -r [text_to_find] *.log because that will only search in folders named [something].log. The reasons for this are complicated.
Questions
- So, how do you grep for a string which contains spaces and quote characters? This is probably some standard feature of Linux Shell syntax which everyone knows, but I don't, and that's why this page needs examples.
- A: Tentatively, you can surround a string with double-quotes and escape any quotes in the search-string with the backslash character. (Single quotes do not seem to work.)
- Likewise, how do you search a group of files? Using "*.*" for FILE doesn't seem to work, and leaving the FILE argument blank tells grep to expect input from STDIN.
- A: apparently "*" by itself; see examples above
Notes
The backtick character ("`") seems to mean "insert the output of this command here" -- so if you're trying to search for a literal backtick, it needs to be escaped with "\" ("\`"). This comes up sometimes when searching for SQL phrases.
Links
- official documentation: more current than the manpage on this server
- Wikipedia