txt2regex: A Shell repository from taiar

txt2regex — The console regular expression wizard

Author: Aurelio Jargas
License: GPL
First release: 2001-02-23
Requires: Bash >= 3.0
Website: https://aurelio.net/projects/txt2regex/

Txt2regex is a regular expression wizard that converts human sentences to regexes. In a simple interactive console interface, the user answer questions and the program builds the regexes for more than 20 flavors like grep, Vim, Emacs, JavaScript, PHP, Python, PostgreSQL.

Txt2regex is a one-file shell script made 100% with Bash builtin commands. The only requirement is Bash itself, since no grep, find, sed or any other system commands are used.

See tests/cmdline.md for a list of all the available command line options and examples on using them.

See tests/features.md for some of the special features txt2regex has to handle user input and compose proper regexes.

Running

Txt2regex is a stand-alone Bash script, it doesn't need to be installed. Just run it:

bash txt2regex.sh

Making it an executable file, you can run it directly:

chmod +x txt2regex.sh
./txt2regex.sh

If you want it in another language besides English:

make install BINDIR=. LOCALEDIR=po
LANG=es_ES ./txt2regex

Supported flavors

$ bash txt2regex.sh --showmeta

awk             +      ?             |      ()    awk version 20121220
chicken         +      ?     {}      |      ()    CHICKEN 4.12.0
ed             \+     \?   \{\}     \|    \(\)    GNU Ed 1.10
egrep           +      ?     {}      |      ()    grep (GNU grep) 3.1
emacs           +      ? \\{\\}    \\|  \\(\\)    GNU Emacs 25.2.2
expect          +      ?     {}      |      ()    expect version 5.45.4
find            +      ?     {}      |      ()    find (GNU findutils) 4.7.0-git
gawk            +      ?     {}      |      ()    GNU Awk 4.1.4
grep           \+     \?   \{\}     \|    \(\)    grep (GNU grep) 3.1
javascript      +      ?     {}      |      ()    node v8.10.0
lex             +      ?     {}      |      ()    flex 2.6.4
mawk            +      ?             |      ()    mawk 1.3.3 Nov 1996
mysql           +      ?     {}      |      ()    mysql  Ver 14.14 Distrib 5.7.29
perl            +      ?     {}      |      ()    perl v5.26.1
php             +      ?     {}      |      ()    PHP 7.2.24-0ubuntu0.18.04.4
postgres        +      ?     {}      |      ()    psql (PostgreSQL) 10.12
procmail        +      ?             |      ()    procmail v3.23pre 2001/09/13
python          +      ?     {}      |      ()    Python 3.6.9
sed            \+     \?   \{\}     \|    \(\)    sed (GNU sed) 4.4
tcl             +      ?     {}      |      ()    tcl 8.6
vi                         \{\}           \(\)    nvi 1.81.6-13
vim            \+     \=    \{}     \|    \(\)    VIM - Vi IMproved 8.0 (2016 Sep 12)

NOTE: . [] [^] and * are the same on all programs.

$

Regex tester to gather "real life" data

Txt2regex needs to know regex-related information for each flavor it supports. For example:

Which metacharacters are supported?
How to escape a metacharacter to match it literally?
Are POSIX character classes supported?

Instead of relying in documentation to get that information, the tests/regex-tester.sh script calls the real programs with specially crafted regexes and sample texts, verifying how those programs behave in "real life".

To have a trackable and public record, the output of this tester is also saved to this repository, in a readable and grepable plain text file: tests/regex-tester.txt. Future changes in behavior can be easily detected.

Testing

make test — to run all the tests in the current Bash version on your machine.
make test-bash — to run all the tests in all the released Bash versions since 3.0 (requires Docker).
make test-regex — to run the regex tester (requires Docker).

Check the Makefile for the details on what gets executed.

Translators

ca       Catalan       Carles (ChAoS)
de_DE    German        Jan Parthey
es_ES    Spanish       Diego Moya
fr_FR    French        wwp
id_ID    Indonesian    Muhamad Faizal
it_IT    Italian       Daniele Pizzolli
ja       Japanese      Hajime Dei
pl_PL    Polish        Chris Piechowicz
pt_BR    Portuguese    Aurelio Jargas
ro_RO    Romanian      Robert Claudiu Gheorghe
tr       Turkish       erayalakese

To translate txt2regex to your language:

translate the po/txt2regex.pot file (in the msgstr lines)
save it as po/XX.po (where XX is the two-letter code for your language)
submit this new .po file in a pull request

Check the current translations for reference.

FAQ

Why?

To try to make simple regexes less painful for beginners.
To have a reliable source for the specific regex syntax and rules from different flavors.
To have coding fun :)

What is that `<TAB>` that appears in the regex?

That <TAB> represents a literal tab character. When using the regex in the desired external program, remember to change that to a literal tab. This is required by programs that do not support using \t as a shortcut for the tab character.

Why my terminal size (lines/columns) is not detected?

Txt2regex uses the environment variables $LINES and $COLUMNS to get the current terminal size. Make sure you have them exported, otherwise the default 80x25 size will be assumed.

To check if the variables are exported, run:

bash -c 'echo $COLUMNS $LINES'

If no numbers are shown in the output, a quick fix is running:

export COLUMNS LINES

As a permanent fix, add the previous export command to a Bash configuration file, such as ~/.bashrc.

taiar/txt2regex