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Not bad, the first time I've seen most that matters about bash scripting in one place. (I miss [[ ]] though.) That said, I try not to do bash scripting. It's a

• mattmight 13y ago
  I was on the fence about adding [[ ]]. I think I'll add it in a revision. I also agree on bash being quirky. I tell my class that the gold standard is a bash script that works 99% of the time.
  • zx2c4 13y ago
    Seconded for [[ and ]]. Also { and } (with semi colons) vs ( and ), for sub processes would be nice to add.
    • lsiebert 13y ago
      I'd also note that your discussion of scope doesn't mention local variables are possible in bash, see: http://www.tldp.org/LDP/abs/html/localvar.html http://www.tldp.org/LDP/abs/html/localvar.html
  • barrkel 13y ago
    I think it might be lacking content on idioms. Things like 'while read -r line; do {stuff with $line}; done' These idioms have issues for their most common uses (e.g. dealing with filenames with embedded newlines), but they do work 99% of the time.
    • unhammer 13y ago
      They work 100 % of the time if you do it right. An example: find . -type f -name foo -print0 | while read -rd ''; do grep -l bar "${REPLY}" done find separates its output with the NUL byte when you do -print0, and -d '' means read NUL-separated input. Of course, in this case it would be better to use: find . -type f -name foo -print0 | xargs -0 -I{} grep -l bar '{}' but if you've got several things to do for each file, the first one makes sense (or you can put those several things in a script, and use xargs).
  • unhammer 13y ago
    http://mywiki.wooledge.org/BashFAQ/031 http://mywiki.wooledge.org/BashFAQ/031 is a great reference. If your guide is for bash and not sh, then I would say don't teach them [, just do [[. It's safer, since it won't glob or split words, you don't need quoting, and you don't need to escape operators like < and >. Maybe it's can be seen as more difficult since it's a sublanguage (doesn't use the regular syntax rules), but so are (( and $(( which you've discussed at length, and which are typically less useful than [[ in bash.
• ufo 13y ago
  What to use instead of bash though? I hate having to worry about all the little quirks in bash but most other languages make simple things like input redirection and piping commands awfully verbose.
  • bakul 13y ago
    rc is pretty minimal and consistent (available in plan9ports).
  • chongli 13y ago
    Haskell! Seriously, people do shell scripting in Haskell. There's actually a pretty nice library designed for it called Shelly: https://github.com/yesodweb/Shelly.hs/blob/master/README.md#usage https://github.com/yesodweb/Shelly.hs/blob/master/README.md#...
    • dllthomas 13y ago
      Shelly is great! Still, there is some minimum complexity before something is better done in it, and porting a small bash script that has grown from a tiny bash script is pretty trivial.
  • jevinskie 13y ago
    Check out IPC::Run for Perl. [0] Perl was already pretty nice with it's backticks but IPC::Run takes it another step further and allows you to do all sorts of redirection/piping/etc with the single 'run' subroutine. If you want an 'expect' sort of use, you can do that too. [0]: http://search.cpan.org/~toddr/IPC-Run-0.92/lib/IPC/Run.pm http://search.cpan.org/~toddr/IPC-Run-0.92/lib/IPC/Run.pm
  • Sir_Cmpwn 13y ago
    I use fish. http://fishshell.com/ http://fishshell.com/ Loop: for f in *.txt cat $f end
    • ufo 13y ago
      Really liking it so far. Thanks for the suggestion.
• dllthomas 13y ago
  I try to keep my scripts extensions of what I'd type at the prompt - often quite directly, yanking it from my history when I realise I need to do something frequently or pulling a line into my editor with with edit-and-execute-command when it gets big (for a single line) and saving it off somewhere. Once it gets above about 10 lines, it's usually time for something else, though I've boiled a few frogs in my day...