strans

strans (string transform) is an intuitive string manipulation utility for the shell (primarily Unix, but should work™ cross-platform). The user does not need to know any programming. All she needs to do is provide strans with a set of examples. strans will automagically learn transformation rules from these examples and apply them to the input given on STDIN.

How to Install

The easiest way to run strans is by installing it via flatpak. It assumes that you have the

flatpak install flathub org.freedesktop.Platform//18.08 org.freedesktop.Sdk//18.08

runtime installed on your system.

After downloading the latest strans.flatpak from releases, install it via

sudo flatpak install strans.flatpak

Note: This standalone Flatpak package will not auto-update.

How to Run

# With before and after example
strans -b pattern-to-match -a desired-transformation

# With file that contains examples
strans -f file-with-examples

# Help page
strans --help

Examples

Example 1: Extract ending of files

Assume that

ls
Document.pdf  Document2.pdf Document.txt  Document.png

Now we want to get a unique list of all file endings present in the directory:

ls | strans -b Document.pdf -a pdf | sort -u

Note how nicely strans (here defined as an alias) integrates with other tools.

Of course, as StackOverflow will tell you, we could obtain the same result with

ls | perl -ne 'print $1 if m/\.([^.\/]+)$/' | sort -u 

But with strans we accomplished the same with much less brain work, without StackOverflow and Perl, but instead with pure joy!

Example 2: Convert full names to their initials

printf "Moritz Beller\nGeorgios Gousios" |
dotnet strans.dll -b "First Last" -a "FL"

neatly outputs

MB
GG

However, when we add a third entry with a middle name, Andy Emil Zaidman, things start to break, as this does not appear in the initials:

MB
GG
AZ

We can fix this by providing strans with another example. We create a file called example-transformations

First Last => FL
Firstname Middlename Lastname => FML

and call

printf "Moritz Beller\nGeorgios Gousios\nAndy Emil Zaidman" |
dotnet strans.dll --example-file example-transformations

And, voila, the output is

MB
GG
AEZ

Note how strans adds the second example and generates a global transformation rule that satisfies all examples given to it. Simply having the last FML example would not be enough, because it would miss the case where only two names are available.

How to Build for Developing

You need dotnet to run strans.

git clone https://github.com/Inventitech/strans.git
cd strans
dotnet restore
dotnet publish -c Release

An alias (in your bashrc, ...) makes strans integrate seamlessly in a Unix environment:

ALIAS strans="dotnet path/to/strans.dll"

Background

strans uses program-by-example techniques from Microsoft PROSE to come up with the rules behind this string manipulation. PROSE allows the creation of extremely complex string transformations within a matter of a few seconds by just giving easy-to-write examples. In its essence, strans is only a light-weight wrapper around and direct application of Microsoft's PROSE framework. strans provides the goodness of the now-removed PowerShell (!) command Convert-String.