Term::ReadLine and line-editing

ibm1620 has asked for the wisdom of the Perl Monks concerning the following question:

I use Term::ReadLine::Gnu for its line-editing and input history retrieval capability. If I forget to install it, I'm reminded the moment I run a script that uses readline, hit the left-arrow at the prompt, and garbage splats out (^[[D). That's my cue to cpanm Term::ReadLine::Gnu.

However, while talking a Mac user through installing a Perl program I wrote that uses readline, I discovered that installing the Gnu version from scratch is harder than I'd thought. First, I had him install the Xcode Command Line Tools as a prerequisite for perlbrew, and then perl v5.34 and cpanm. But cpanm Term::ReadLine::Gnu failed: The libreadline you are using is the libedit library. Use the GNU Readline Library. The simplest solution to this I could find involved installing homebrew. Homebrew's easy enough for me to use, but I felt like I was expending an awful lot of effort to provide a Mac terminal user with basic command-line editing.

Long story short, I installed Term::ReadLine::Perl and it mostly works (haven't fully tested it yet) but, because my prompt uses sequences from Term::ANSIColor, it writes '0m ' after the prompt! And if I remove those sequences, my keystrokes appear in white.

Since I normally don't have this kind of trouble doing something easy in Perl, I figure I'm overlooking something very obvious. Readline-Gnu "just worked" for me; can't Readline-Perl do the same, at least for line editing and input retrieval?

Comment on Term::ReadLine and line-editing

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Re: Term::ReadLine and line-editing by kcott (Archbishop) on May 06, 2022 at 00:14 UTC
G'day ibm1620, I encountered similar problems and documented the fix in "cpan: Terminal does not support AddHistory.". You may find some help there; although, do note it's a different OS (but does use Perlbrew). — Ken	[reply]
Re^2: Term::ReadLine and line-editing by ibm1620 (Hermit) on May 06, 2022 at 13:50 UTC
Hi Ken, Thanks for the suggestion. Unfortunately, downloading and manually make'ing Term::ReadLine::Gnu produced the same error about the libreadline I'm using being the libedit library. I suspect that this problem may be specific to MacOS.	[reply]
Re: Term::ReadLine and line-editing by Discipulus (Canon) on May 06, 2022 at 08:06 UTC
Hello ibm1620, from what I understand you should use Term::ReadLine as frontend, not directly Term::ReadLine::Gnu or ::Perl you can control with the env var `PERL_RL` which one is loaded. This is the standard way. That said you can find interesting easy-osx-termreadlinegnu and this SO post but basically they both say to: `brew install readline brew link --force readline cpanm Term::ReadLine::Gnu brew unlink readline` [download] L* There are no rules, there are no thumbs.. Reinvent the wheel, then learn The Wheel; may be one day you reinvent one of THE WHEELS.	[reply] [d/l] [select]
Re^2: Term::ReadLine and line-editing by ibm1620 (Hermit) on May 06, 2022 at 12:30 UTC
Hi Discipulus, I know about PERL_RL, my problem is that ::Perl creates visual blemishes in my prompt, and that installing ::Gnu is so complicated on a Mac that doesn't have developer tools. Although I'd gone ahead and had my client install Xcode COmmand Line Tools as prerequesite to installing perlbrew, simply to create a local Perl environment in which to install a readline module, it turned out that `cpanm Term::ReadLine::Gnu` would require homebrew in order to install readline-gnu, at which point I decided (with a little exasperation) to try installing ::Perl instead. I'm still waiting to hear back about whether kcott's suggestion above (make'ing ::Gnu manually) worked for my client. Unfortunately my two Macs both have Xcode and homebrew so I can't test. I hope I haven't muddied the waters further! :-)	[reply] [d/l]