Set bash's shell option nullglob by default?
Hi, I have a question about nullglob bash's shell option. I want to hear opinions. The behavior is nicely described in bash reference manual [1] By default, the nullglob is turned off. And it tends people to use bad habits in shell scripting. In my POV the nullglob could be turned on by default. However, i would like to hear opinions from others. It is possible it can break many scripts even in rpm's scriptlets, but as I already said, it's because bad habits. So the main gain will be the people will learn how is the globbing in bash and in the whole environment working. RR [1] http://www.gnu.org/software/bash/manual/bashref.html#Filename-Expansion -- devel mailing list devel@lists.fedoraproject.org https://admin.fedoraproject.org/mailman/listinfo/devel
Re: Set bash's shell option nullglob by default?
On Fri, Jul 13, 2012 at 01:56:29PM +0200, Roman Rakus wrote: Hi, I have a question about nullglob bash's shell option. I want to hear opinions. The behavior is nicely described in bash reference manual [1] By default, the nullglob is turned off. And it tends people to use bad habits in shell scripting. In my POV the nullglob could be turned on by default. However, i would like to hear opinions from others. It is possible it can break many scripts even in rpm's scriptlets, but as I already said, it's because bad habits. So the main gain will be the people will learn how is the globbing in bash and in the whole environment working. So ls *.foo should list the entire directory if no files match *.foo? It's a bad habit for me to expect ls *.foo to return nothing in this case? You're going to need to convince me. -- Scott Schmit smime.p7s Description: S/MIME cryptographic signature -- devel mailing list devel@lists.fedoraproject.org https://admin.fedoraproject.org/mailman/listinfo/devel
Re: Set bash's shell option nullglob by default?
On 07/13/2012 02:06 PM, Scott Schmit wrote: So ls *.foo should list the entire directory if no files match *.foo? It's a bad habit for me to expect ls *.foo to return nothing in this case? You're going to need to convince me. And if there are directories ending with .foo? Hopefully you are not using such things in scripts. OK, in interactive shells `ls *' is not that wrong. printf '%s\n' *.foo for file in *.foo; do ... done RR -- devel mailing list devel@lists.fedoraproject.org https://admin.fedoraproject.org/mailman/listinfo/devel
Re: Set bash's shell option nullglob by default?
On Fri, 2012-07-13 at 13:56 +0200, Roman Rakus wrote: Hi, I have a question about nullglob bash's shell option. I want to hear opinions. The behavior is nicely described in bash reference manual [1] By default, the nullglob is turned off. And it tends people to use bad habits in shell scripting. In my POV the nullglob could be turned on by default. However, i would like to hear opinions from others. This could cause serious surprising breakages of scripts with strange consequences. I'm strictly against this change. If something at all should be changed in this regard to break bad habits then it should be the failglob option although I am not convinced that it is too good idea either. -- Tomas Mraz No matter how far down the wrong road you've gone, turn back. Turkish proverb -- devel mailing list devel@lists.fedoraproject.org https://admin.fedoraproject.org/mailman/listinfo/devel
Re: Set bash's shell option nullglob by default?
On 07/13/2012 02:19 PM, Tomas Mraz wrote: This could cause serious surprising breakages of scripts with strange consequences. I'm strictly against this change. If something at all should be changed in this regard to break bad habits then it should be the failglob option although I am not convinced that it is too good idea either. I was thinking about failglob also, but it is not that useful like it looks. for name in *; do ...; done In the current state, if there isn't any file, the name variable will contain *. With nullglob name will be empty and script continues after the for loop. With failglob it will print error message. I think it is not useful. But you are right, it will cause many breakages (even surprising). RR -- devel mailing list devel@lists.fedoraproject.org https://admin.fedoraproject.org/mailman/listinfo/devel
Re: Set bash's shell option nullglob by default?
-BEGIN PGP SIGNED MESSAGE- Hash: SHA1 On 07/13/2012 01:06 PM, Scott Schmit wrote: On Fri, Jul 13, 2012 at 01:56:29PM +0200, Roman Rakus wrote: Hi, I have a question about nullglob bash's shell option. I want to hear opinions. The behavior is nicely described in bash reference manual [1] By default, the nullglob is turned off. And it tends people to use bad habits in shell scripting. In my POV the nullglob could be turned on by default. However, i would like to hear opinions from others. It is possible it can break many scripts even in rpm's scriptlets, but as I already said, it's because bad habits. So the main gain will be the people will learn how is the globbing in bash and in the whole environment working. So ls *.foo should list the entire directory if no files match *.foo? It's a bad habit for me to expect ls *.foo to return nothing in this case? You're going to need to convince me. I wouldn't back this change either but that's not the behaviour of nullglob. If nothing matches the glob the word remains unchanged (i.e. *.foo - *.foo): $ ls *.foo ls: cannot access *.foo: No such file or directory $ echo *.foo *.foo Regards, Bryn. -BEGIN PGP SIGNATURE- Version: GnuPG v1.4.12 (GNU/Linux) Comment: Using GnuPG with Mozilla - http://enigmail.mozdev.org/ iEYEARECAAYFAlAAFTIACgkQ6YSQoMYUY956BgCgicpLdJr4nM7NBwYOSJS9kQVe 8qoAoJKEtqaWJ0SAbT2UXK7URkSaxXV+ =H6xC -END PGP SIGNATURE- -- devel mailing list devel@lists.fedoraproject.org https://admin.fedoraproject.org/mailman/listinfo/devel
Re: Set bash's shell option nullglob by default?
-BEGIN PGP SIGNED MESSAGE- Hash: SHA1 On 07/13/2012 01:31 PM, Bryn M. Reeves wrote: I wouldn't back this change either but that's not the behaviour of nullglob. If nothing matches the glob the word remains unchanged (i.e. *.foo - *.foo): Eh, nevermind.. not enough coffee. Bryn. -BEGIN PGP SIGNATURE- Version: GnuPG v1.4.12 (GNU/Linux) Comment: Using GnuPG with Mozilla - http://enigmail.mozdev.org/ iEYEARECAAYFAlAAFYMACgkQ6YSQoMYUY94DnACgkaZ3RgDOq98rMsVREgwYMBnG fokAoI9qRfmYOpIv9wzq7u7VMCMCq1zv =MTCR -END PGP SIGNATURE- -- devel mailing list devel@lists.fedoraproject.org https://admin.fedoraproject.org/mailman/listinfo/devel
Re: Set bash's shell option nullglob by default?
Roman Rakus wrote: By default, the nullglob is turned off. And it tends people to use bad habits in shell scripting. What habits exactly, and why are those habits bad? In my POV the nullglob could be turned on by default. However, i would like to hear opinions from others. Changing a programming language under the programmers' feet it almost never a good idea. Shall I start setting all Bash options explicitly in every single shell script just so that I'll know how the language works even if someone changes the defaults on me? Björn Persson signature.asc Description: This is a digitally signed message part. -- devel mailing list devel@lists.fedoraproject.org https://admin.fedoraproject.org/mailman/listinfo/devel
Re: Set bash's shell option nullglob by default?
Roman wrote: It is possible it can break many scripts even in rpm's scriptlets, but as I already said, it's because bad habits. So the main gain will be the people will learn how is the globbing in bash and in the whole environment working. Please don't. If an author or maintainer wants to save themself from bad habits, they can put shopt -s nullglob near the top of their bash scripts. Let's not break many, many existing scripts. David -- devel mailing list devel@lists.fedoraproject.org https://admin.fedoraproject.org/mailman/listinfo/devel
