5 ms·

Lousiness of the unix shell? The shell is beautiful and useful and not in any way lousy. It's not supposed to be a programming language, in fact, the only pla

by leif 16y ago

Lousiness of the unix shell? The shell is beautiful and useful and not in any way lousy. It's not supposed to be a programming language, in fact, the only places it's used as such are places where it's unreasonable to expect a system will have anything else (autoconf and friends). When's the last time you used perl, tcl, python, ruby, or anything but the shell as an interactive prompt to invoke other programs? If I may: filter () { read p && echo $p || exit while read x; do if [ `expr $x % $p` != 0 ]; then echo $x fi done | filter }

mahmud 16y ago
You managed to cherry-pick the few Good Parts. Question for you: what is the syntax for declaring a variable, initializing the variable, referencing the variable later, and assigning the value of that variable to another variable? ;-) Now that I have refreshed your memory, do you still insist it's not lousy? For the innocent bystanders, here is how those steps are: set var # just creating the variable .. easy # but set is a configurable command! # see your "sh" variety man for more info set var=value # no space on either side of '='! # 'value' can only be one word string, # number or character. # because single characters are # ubiquitous in nature .. # chars chars, everywhere # if you want a multiword string, use () # or "a raw string with spaces" # unless you want $ not to be expanded # then use 'raw constant string' # and if you want to run a program and # insert its output into the string .. # use "`program`" # did I say you can't put spaces around =? # eskooz me, I am just dereferencing var set newvar=$var # need a magic syntax, it's teh C ptr # unless you want the *whole* value # then you use ($var) or was it $(var)? # again, ask your sh variety manpage # I love portability # if $var isn't bound, use $?var to test # we said 'set' is a command above # so using unbound var is .. # dependant (sic) on settings # if var contains multiple words (why is that a unit # of input neway?) you can index it and count elements # with $#var and $var[i] respectively; we made everything # an external command or built in, but LENGTH and INDEX # need to be special syntax, because they're more vital # than goddamn assignment (which is fine being a builtin)
- sprout 16y ago
  Again, it is not a programming language. The shell is designed to do things you think about for less than 10 seconds. If you're trying to reference a variable you used earlier, that's not what it's for. You don't store things in the shell. You create very quick and dirty statements to make data look cleaner.
  - mahmud 16y ago
    I actually agree with you. If all you use the shell for is to launch programs, do basic job control and redirect I/O and do some basic pipelines, then you should be fine. But keep in mind that 10s shell solutions becomes week long problems the moment you save them into a file. I have complex commands, either stored in a function or grepped from my history ;-) but my initial response was to the author, and anyone who laments the shell's shortcomings for anything more "industrial" than a one liner. I was strictly answering the premise in the fifth panel: http://shellhaters.heroku.com/#5 http://shellhaters.heroku.com/#5 "Also, Programming Language" That it's not. Use your favorite language for your N-liners, for N > 1.
    - gaius 16y ago
      One-off scripts never are. You reuse them and tweak them for slightly different scenarios, then figure, I'll make it a parameter. Then something goes wrong and you add some error checking. Then you show it to someone else or put it in a cron job or whatever and you write some documentation. Before you know it, your little script is no only a permanent fixture, but other people are relying on it, or its output, or reusing one of its functions. I've seen 10-line file mungers end up as 1000-line batch jobs. Don Stewart at Galois even advocates using Haskell for what was traditionally done with shell scripts http://www.scribd.com/doc/36045849/Practical-Haskell-Programming-scripting-with-types http://www.scribd.com/doc/36045849/Practical-Haskell-Program...
      - leif 16y ago
        Well, this is how we got stuck with autoconf (of course, then some genius decided m4 was a good idea). Interestingly, sh (at least, the common intersection of all the shells) is a good choice for a language that needs to bootstrap, since pretty much every unix machine has an implementation installed somewhere by default. The way they used it was a little wonky, and if we could go back in time I'd probably suggest generating the configure script from a better language than m4, but it's not the worst of all possible worlds. That is a cool link, thanks for sharing! Somewhere there's a similar article with OCaml that I never got all the way through, though maybe it was more about systems programming than system administration (so, replacing C, not sh).
gojomo 16y ago
...beautiful and useful and not in any way lousy... You have SHtockhome SHyndrom.
forkandwait 16y ago
Whether or not the shell is good depends (like everything) on what you are trying to do with it. For an interactive console, I find bash (with the completion package and a custom prompt) better than anything I have ever used (and I keep trying to find a replacement). For programming, sh is great at matching and moving files en masse depending on a few parameters, or wrapping cron jobs, and the like. For this it is downright delicious, but for things outside its domain, it rather sucks just like any programming language.

by leif 16y ago

mahmud 16y ago

You managed to cherry-pick the few Good Parts. Question for you: what is the syntax for declaring a variable, initializing the variable, referencing the variable later, and assigning the value of that variable to another variable? ;-) Now that I have refreshed your memory, do you still insist it's not lousy? For the innocent bystanders, here is how those steps are: set var # just creating the variable .. easy # but set is a configurable command! # see your "sh" variety man for more info set var=value # no space on either side of '='! # 'value' can only be one word string, # number or character. # because single characters are # ubiquitous in nature .. # chars chars, everywhere # if you want a multiword string, use () # or "a raw string with spaces" # unless you want $ not to be expanded # then use 'raw constant string' # and if you want to run a program and # insert its output into the string .. # use "`program`" # did I say you can't put spaces around =? # eskooz me, I am just dereferencing var set newvar=$var # need a magic syntax, it's teh C ptr # unless you want the *whole* value # then you use ($var) or was it $(var)? # again, ask your sh variety manpage # I love portability # if $var isn't bound, use $?var to test # we said 'set' is a command above # so using unbound var is .. # dependant (sic) on settings # if var contains multiple words (why is that a unit # of input neway?) you can index it and count elements # with $#var and $var[i] respectively; we made everything # an external command or built in, but LENGTH and INDEX # need to be special syntax, because they're more vital # than goddamn assignment (which is fine being a builtin)

sprout 16y ago
Again, it is not a programming language. The shell is designed to do things you think about for less than 10 seconds. If you're trying to reference a variable you used earlier, that's not what it's for. You don't store things in the shell. You create very quick and dirty statements to make data look cleaner.
- mahmud 16y ago
  I actually agree with you. If all you use the shell for is to launch programs, do basic job control and redirect I/O and do some basic pipelines, then you should be fine. But keep in mind that 10s shell solutions becomes week long problems the moment you save them into a file. I have complex commands, either stored in a function or grepped from my history ;-) but my initial response was to the author, and anyone who laments the shell's shortcomings for anything more "industrial" than a one liner. I was strictly answering the premise in the fifth panel: http://shellhaters.heroku.com/#5 http://shellhaters.heroku.com/#5 "Also, Programming Language" That it's not. Use your favorite language for your N-liners, for N > 1.
  - gaius 16y ago
    One-off scripts never are. You reuse them and tweak them for slightly different scenarios, then figure, I'll make it a parameter. Then something goes wrong and you add some error checking. Then you show it to someone else or put it in a cron job or whatever and you write some documentation. Before you know it, your little script is no only a permanent fixture, but other people are relying on it, or its output, or reusing one of its functions. I've seen 10-line file mungers end up as 1000-line batch jobs. Don Stewart at Galois even advocates using Haskell for what was traditionally done with shell scripts http://www.scribd.com/doc/36045849/Practical-Haskell-Programming-scripting-with-types http://www.scribd.com/doc/36045849/Practical-Haskell-Program...
    - leif 16y ago
      Well, this is how we got stuck with autoconf (of course, then some genius decided m4 was a good idea). Interestingly, sh (at least, the common intersection of all the shells) is a good choice for a language that needs to bootstrap, since pretty much every unix machine has an implementation installed somewhere by default. The way they used it was a little wonky, and if we could go back in time I'd probably suggest generating the configure script from a better language than m4, but it's not the worst of all possible worlds. That is a cool link, thanks for sharing! Somewhere there's a similar article with OCaml that I never got all the way through, though maybe it was more about systems programming than system administration (so, replacing C, not sh).

gojomo 16y ago

...beautiful and useful and not in any way lousy... You have SHtockhome SHyndrom.

forkandwait 16y ago

Whether or not the shell is good depends (like everything) on what you are trying to do with it. For an interactive console, I find bash (with the completion package and a custom prompt) better than anything I have ever used (and I keep trying to find a replacement). For programming, sh is great at matching and moving files en masse depending on a few parameters, or wrapping cron jobs, and the like. For this it is downright delicious, but for things outside its domain, it rather sucks just like any programming language.