Replace

  • Text replacement: 

    1$ sed 's/string to replace/replacement string/g' original-file.txt > new-file.txt

  • Dynamic, in-place replacement of unreleased text with today’s date: 

    1$ sed -i "s/unreleased/`date +'%Y-%m-%d'`/" ./changelog.md

  • Update the release date in citation.cff file: 

    1$ perl -pi -e "s/date-released: \d+-\d+-\d+/date-released: $(date +'%Y-%m-%d')/" ./citation.cff

  • Replace all occurrences of str1 by str2 in all files below the /folder path: 

    1$ find /folder -type f -print -exec sed -i 's/str1/str2/g' "{}" \;

  • Same as above but ignore all content of .svn folders and .zip files: 

    1$ find /folder -type f -not -regex ".*\/\.svn\/.*" -not -iname "*\.zip" -print -exec sed -i 's/str1/str2/g' "{}" \;

  • Remove trailing spaces and tabs in every XML files: 

    1$ find /folder -iname "*.xml" -exec sed -i 's/[ \t]*$//' "{}" \;

  • Place a new --- line at the start of each .markdown files ( see result  ): 

    1$ find ./folder -iname "*.markdown" -exec sed -i '1s/^/---\n/' "{}" \;

  • Place a new --- line before the first empty line of each .markdown files ( see result  ): 

    1$ find ./folder -iname "*.markdown" -exec sed -i '0,/^$/s//---\n/' "{}" \;

  • Remove lines starting with prefix1: or prefix2: in all .markdown files: 

    1$ find /folder -iname "*.markdown" -exec perl -p -i -e 's/(prefix1|prefix2): .*\n//sg' "{}" \;

  • Strip time from date: prefixed lines and quote the value. I.e. replace all occurrences of date: 2012-01-01 00:00:00 +0000 by date: "2012-01-01" : 

    1$ find /folder -iname "*.markdown" -exec perl -p -i -e 's/date: (\d+-\d+-\d+) .*\n/date: "$1"\n/sg' "{}" \;

  • Remove in all .markdown files all occurrences of Amazon’s pixel tracking links in the form of ![](https://www.assoc-amazon.com…) : 

    1$ find ./* -iname "*.md" -exec perl -0777 -i -pe "s/\!\[\]\(https:\/\/www\.assoc-amazon\.com.*?\)//gs" "{}" \;

  • Shorten in all .markdown files Amazon’ product URLs from (https://www.amazon.com/dp/B00F3F0GLU/?tag=accounid-20) to (https://amzn.com/B00F3F0GLU/?tag=accounid-20) : 

    1$ find ./* -iname "*.md" -exec perl -0777 -i -pe "s/\(https:\/\/www\.amazon\.com\/dp\/(.*?)\)/\(https:\/\/amzn\.com\/\1\)/gs" "{}" \;

  • Remove lines matching a regex (encoding particular markdown TOC entries ), save the result in place and save a backup of the original content in a .bak file: 

    1$ gawk -i inplace -v INPLACE_SUFFIX=.bak '!/^- \[(Contribute|Contributing|Licence|License)\]\(#.+\)$/{print}' ./readme.md

  • Use sed address ranges to spot, in a Markdown file, all blocks led by a ::: directive, and terminated by a blank line. Then replace in each of these matched blocks the a letter by XXX . Notice how a occurrences outside the blocks are not replaced by XXX : 

    $ cat ./example.md

This is a code block:

:::shell-session
→ apache
→ java
→ python

This is another block:

:::shell-session
→ rust
→ haskell
→ javascript

This is a random sentence.

$ sed "/^:::/,/^$/ s/a/XXX/g" ./example.md

This is a code block:

:::shell-session
→ XXXpXXXche
→ jXXXvXXX
→ python

This is another block:

:::shell-session
→ rust
→ hXXXskell
→ jXXXvXXXscript

This is a random sentence.

  • In the same spirit as above but this time to spot indented blocks starting with ::: , then wrap them into triple-backticks fences: 

    $ cat ./example.md

This is a code block:

    :::shell-session
    → apache
    → java
    → python

This is another block:

    :::shell-session
    → rust
    → haskell
    → javascript

This is a random sentence.

$ find ./folder -iname "*.md" \
> -exec sed -i "/^    :::/,/^$/ s/^$/    \`\`\`\n/" "{}" \; \
> -exec sed -i "/^    :::/,/^$/ s/:::/\`\`\`/"      "{}" \;

$ cat ./example.md

This is a code block:

    ```shell-session
    → apache
    → java
    → python
    ```

This is another block:

    ```shell-session
    → rust
    → haskell
    → javascript
    ```

This is a random sentence.

  • Strip in-place the block of text starting with XXX and ending with an empty line: 

    $ cat ./example.md

This is a code block:

XXX{shell-session}
→ apache
→ java
→ python

This is a random sentence.

$ perl -i -ne "print if not /XXX/ .. /^$/" ./example.md

$ cat ./example.md

This is a code block:

This is a random sentence.

  • Same as above, but with sed : 

    1$ sed -i "/^XXX/,/^$/ d" ./example.md

  • Python one-liner to delete the first occurrence of a block of text delimited by triple-backticks fences. Contrary to methods above, this one is not distracted by blank lines within the text block: 

    1$ python -c 'import re; from pathlib import Path; file = Path("./example.md"); file.write_text(re.sub(r"^\`\`\`.*?\`\`\`\n\n", "", file.read_text(), count=1, flags=re.MULTILINE | re.DOTALL))'

  • Append the content of the addendum.txt file to all .markdown files: 

    1$ find ./folder -iname "*.markdown" -print -exec bash -c 'cat ./addendum.txt >> "{}"' \;

  • Replace all accentuated characters by their non-accentuated variants (thanks Matthieu for the tip): 

    1$ echo "éÈça-$" | iconv -t ASCII//translit

Date & Time

  • Get the date of last week: 

    1$ date +"%Y-%m-%d" -d last-week

  • Get the current date in english: 

    1$ env LC_TIME=en date +"%a %b %d %Y"

  • Get the number of seconds since epoch  : 

    1$ date +%s

  • Convert back epoch time to human-readable date: 

    1$ date --date=@1234567890

Transcoding

  • In place charset transcoding: 

    1$ recode utf-8..latin-1 utf8text.txt

Edition

Additional References