On Tue, Dec 8, 2020 at 8:49 PM Chet Ramey <chet.ra...@case.edu> wrote:
> On 12/8/20 6:32 PM, Lawrence Velázquez wrote: > > > Such information could just be added to the output of bash --version > > (or perhaps as a shell variable à la BASH_VERSION). There is no > > need for a separate command-line option. > > Why, though? What is valuable about knowing which version of readline is > linked with a particular bash binary? (Or, more accurately, knowing > whether or not that bash binary is linked with an external version of > readline, knowing that specific bash versions are always shipped with > specific readline versions.) > > -- > ``The lyf so short, the craft so long to lerne.'' - Chaucer > ``Ars longa, vita brevis'' - Hippocrates > Chet Ramey, UTech, CWRU c...@case.edu http://tiswww.cwru.edu/~chet/ ---------- BACKGROUND: ---------- In Appendix A of the official Bash manual, it says that "suggestions and ‘philosophical’ bug reports" are requested — so please bear with me while I get a bit philosophical about the experience that led to this thread. I'll begin with a bit of demographic perspective: If we divide the entire Bash user base into three categories — beginner, intermediate and advanced — I would arbitrarily guess that only 2% are truly "advanced". This elite demographic would certainly *NOT* include me — but it would include many of the people on the bug-bash mailing list. They live and breathe this stuff — they have a deep understanding of Bash and its configuration. They also have a mastery of the C language and are therefore able to properly interpret the implications of the Bash source code. The overwhelming majority of Bash users, however, do not fit this description. ------------- MY EXPERIENCE: ------------- When Bash 5.1 came out two days ago, I was excited to build it and try it! However, since I knew the latest version of Bash was dependent on the latest version of Readline in order to work properly, it was reasonable for a non-expert like me to assume that Readline also needed to be built. This is especially true since I could find no step-by-step building instructions or clear-cut requirements in either the online or offline documentation. Nonetheless, as an experiment, I went ahead and built Bash 5.1 anyway — without first building its core dependency, Readline 8.1. I was surprised to discover that everything worked perfectly! And, when I pasted a script into LXTerminal, all the pasted text was selected / highlighted by default — a brand-new behavior. That was my tip-off that my build of Bash 5.1 was somehow using Readline 8.1 — even though I had not consciously done anything to build or install it. So, on my Debian Buster-based Raspberry Pi OS system, I ran this command line to search for all Readline-related packages: sudo apt list --installed | grep readline And this was the output: libreadline-dev/stable,now 7.0-5 arm64 [installed] libreadline7/stable,now 7.0-5 arm64 [installed] readline-common/stable,stable,now 7.0-5 all [installed] And indeed, 7.0 is the Readline version that currently comes with Debian: https://packages.debian.org/source/buster/readline Yet I also know that 5.0 is the Bash version that currently comes with Debian — so I was a bit surprised that Debian's version of Bash wasn't accompanied by its "sister" package — Readline 8.0: https://packages.debian.org/buster/bash ---------- CONCLUSION: ---------- It was at this point that I realized the latest version of Readline must have been included with the Bash source code — and that I didn't need to do anything more. Nonetheless, like any good "amateur scientist" that wasn't sure about his theory, it was only natural to see if I could confirm my hypothesis. Bash is a critical piece of software to me — so I wanted to make sure that everything was proper. I assumed it would be a simple task. But I was surprised to discover that there was no easy way to determine what version of Readline my copy of Bash was using — even though Bash is intimately dependent on having the proper version of Readline. Instead, on a third-party website, after a full hour of searching, I finally discovered an obscure external method to confirm that my copy of Bash was using the right version of Readline. A further layer of complication, as this thread clearly illustrates, is that the output of that external method is not intuitive to the 98% of non-experts. And there it is — the full story of the multi-hour rabbit hole I fell into in my seemingly simple quest — to determine what version of Readline that Bash is using! I'm obviously biased by my personal experience — and how involved it turned out to be. Nonetheless, I think it would be very helpful if that fundamental information could eventually be added to the output of: bash --version
