https://github.com/shalomb/hl

colourise/highlight text output - like grep but without suppressions
https://github.com/shalomb/hl

grep grep-like highlight-text hl perl6 perl6-regex perl6-scripts raku raku-regex regex

Last synced: 14 days ago
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colourise/highlight text output - like grep but without suppressions

• Host: GitHub
• URL: https://github.com/shalomb/hl
• Owner: shalomb
• License: other
• Created: 2017-06-27T12:05:01.000Z (over 7 years ago)
• Default Branch: master
• Last Pushed: 2017-06-30T13:36:55.000Z (over 7 years ago)
• Last Synced: 2024-11-11T22:25:45.940Z (2 months ago)
• Topics: grep, grep-like, highlight-text, hl, perl6, perl6-regex, perl6-scripts, raku, raku-regex, regex
• Language: Perl6
• Homepage:
• Size: 500 KB
• Stars: 0
• Watchers: 3
• Forks: 0
• Open Issues: 0
• Metadata Files:
  • Readme: README.md
  • License: LICENSE

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README

        
# Name

hl

# Synopsis

Colourise and highlight text in an output stream

# Usage

    hl  [|-|< |< <()]

    [shell_expression|command] | hl 

# Environmental Variables

    HL_COLOURS=',' # CSV spec as per Terminal::ANSIColor

# Description

`hl` paints text regions of an output stream or file indicated by a given

[Perl 6 regular expressions](https://docs.perl6.org/language/regexes).

This is useful when you are looking for patterns 

in text but would like to preserve the context around it 

(like `grep` but not suppressing any output).

hl emerges out of a hacky (unreliable) bash alias I had lying around and the

need to [learn some practical Perl 6](https://www.learningperl6.com/).

# Examples

### Highlight pattern matches

The simplest use case - matching a word.

    hl root /etc/passwd

![highlight-simple](doc/highlight-simple.png)

Here is an example using a more advanced (albeit trite) Perl6 regular expression

    hexdump /bin/cat |

      hl '<-[0\s]+[1..9a..f]> ** 2..4'

![highlight-01](doc/highlight-01.png)

### Highlight text fields

Sometimes highlighting fields helps us find anomalies

    hl '<-[:]>* ' /etc/passwd

![fields](doc/fields.png)

### Highlight blocks of text

If you need a visual aid while staring at or reading from long blocks of text

    hexdump -n $((64*16)) -v -e '/1 "%02x"' -e '/64 "\n"' /dev/urandom |

      hl '. ** 8'

![blocks](doc/blocks.png)

### π maze

And here's something fun with some [digits of π](https://www.angio.net/pi/digits/100000.txt)

    perl -lne 'print for /.{64}/g' pi-100000.txt |

      tail -n 32 | 

      HL_COLOURS='244 on_120, 244 on_255' hl '<[02468]>' |

      HL_COLOURS='45 on_24'               hl '(^|) <[13579]>+' 

![pi-maze](doc/pi-maze.png)

# See Also

* [github.com/ap/hl](https://github.com/ap/hl) -

  [Aristotle Pagaltzis](http://plasmasturm.org/)'s version of `hl` in perl 5

* [docs.perl6.org/language/regexes](https://docs.perl6.org/language/regexes#Literals)

  for reference on using Perl 6 Regular Expressions.

* [github.com/tadzik/Terminal-ANSIColor](https://github.com/tadzik/Terminal-ANSIColor)

  for colour specifications that `hl` uses via the `HL_COLOURS` environmental

  variable.

# TODO

* `hl` can be really slow for large amounts of input text.

* Suppress lines not matching patterns _a la_ grep.

* Support for highlighting individual regex captures.

* Support for nested regex captures.

* Detecting 256-colour capable terminals and falling back.