Text Processing: Recursive search and replace: Difference between revisions

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Where:


* <code>grep</code>: <code>-Z</code>, <code>--null</code> - a data line ends in 0 byte, not newline (null delimiter);
* <code class="noTypo">grep</code>: <code class="noTypo">-Z</code>, <code class="noTypo">--null</code> - a data line ends in 0 byte, not newline (null delimiter);
* <code>grep</code>: <code>-l</code>, <code>--files-with-matches</code> - print only names of FILEs with selected lines;
* <code class="noTypo">grep</code>: <code class="noTypo">-l</code>, <code class="noTypo">--files-with-matches</code> - print only names of FILEs with selected lines;
* <code>xargs</code>: <code>-0</code> <code>--null</code> - items are separated by a null, not white-space; disables quote and backslash processing and logical EOF processing;
* <code class="noTypo">xargs</code>: <code class="noTypo">-0</code> <code class="noTypo">--null</code> - items are separated by a null, not white-space; disables quote and backslash processing and logical EOF processing;
* <code>sed</code>: <code>s</code> - substitute <code>/old/new/</code>, <code>g</code> - all matches to the end of the line; <code>-i.bak</code> do the changes in place and create a backup file.  
* <code class="noTypo">sed</code>: <code class="noTypo">s</code> - substitute <code class="noTypo">/old/new/</code>, <code class="noTypo">g</code> - all matches to the end of the line; <code class="noTypo">-i.bak</code> do the changes in place and create a backup file.  


Simple example:
<syntaxhighlight lang="shell" line="1" class="mlw-shell-gray">
grep -rliZ 'hw\.2022' | xargs -0 sed 's#hw\.2022#homework/hw.2022#g' -i.bak
</syntaxhighlight>
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Revision as of 12:00, 4 August 2022

Lin­ux Serv­er

Re­cur­sive search with Grep

grep -rni 'string or regexp' *

Where:

  • * – will match to all files and di­rec­to­ries (which doesn't start with ., al­ter­na­tive­ly you may need to use ./ to match every­thing with­in the cur­rent di­rec­to­ry;
  • -r, --recursive – in this case works to­geth­er with * (or ./);
  • -n, --line-number – out­put the line num­ber where the match is found,
  • -i, --ignore-case – do case in­sen­si­tive match.

Re­cur­sive re­place with Grep, Xargs and Sed

SEARCHED="string or regexp"
REPLACEMENT="string"

Dry run:

grep -rlZ "$SEARCHED" * | xargs -0 sed 's/${SEARCHED}/${REPLACEMENT}/g'

grep -rlZ "$SEARCHED" * | xargs -0 sed 's/${SEARCHED}/${REPLACEMENT}/g' | grep "$REPLACEMENT"

Re­place: 

grep -rlZ "$SEARCHED" * | xargs -0 sed 's/${SEARCHED}/${REPLACEMENT}/g' -i.bak

Where:

  • grep: -Z, --null – a da­ta line ends in 0 byte, not new­line (null de­lim­iter);
  • grep: -l, --files-with-matches – print on­ly names of FILEs with se­lect­ed lines;
  • xargs: -0 --null – items are sep­a­rat­ed by a null, not white-space; dis­ables quote and back­slash pro­cess­ing and log­i­cal EOF pro­cess­ing;
  • sed: s – sub­sti­tute /old/new/, g – all match­es to the end of the line; -i.bak do the changes in place and cre­ate a back­up file.

Sim­ple ex­am­ple: 

grep -rliZ 'hw\.2022' | xargs -0 sed 's#hw\.2022#homework/hw.2022#g' -i.bak
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