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[Help-bash] pass command to script
From: |
Warlich, Christof |
Subject: |
[Help-bash] pass command to script |
Date: |
Fri, 26 Apr 2019 07:24:01 +0000 |
> $ time var="Hello cruel" bash -c 'echo "${var} world!"; sleep 2; echo
> "Goodbye World!"'
> Hello cruel world!
> Goodbye World!
>
> real 0m2,007s
> user 0m0,001s
> sys 0m0,006s
Thanks for all of your enlightening comments, though I'm a bit disappointed
that no one addressed why bash's "time" builtin obviously does so well! Sure,
as a builtin, it may "see" the string being passed _before_ it has been
tinkered with by the shell. Nevertheless, I wonder if that very fact could lead
one way to find a good solution?! Considering programs like ssh, it looks like
there are quite a few applications that would significantly benefit.
Pondering on how to pass commands to a script _without_ having the shell
tinkering with it before, enclosing the whole command string into single quotes
comes into mind - but unfortunately, this fails miserably when the command
itself contains single quotes. Even any attempt to escape inner single quotes
seems to be doomed. E.g., the following causes the shell to to ask for further
input:
$ ls '\'foo\''
>
Obviously, single quotes even prevent the backslash to be interpreted by the
shell.
Luckily, $'...' quoting comes to a rescue here:
$ ls $'\'foo\''
ls: cannot access 'foo': No such file or directory
But it just adds only _one_ additional layer of nesting, so it is still easy to
find examples of command lines (that already used up all possible quote-nesting
by itself) that would not work. Furthermore, the backslashes really look ugly.
To me, the almost prefect solution would be if bash offered some sort of
nestable quotes right away, e.g. something like $[], which may not already be
in use afaik. What do you think? Would this be a desirable (and decently easily
implementable) feature for bash?
Cheers,
Chris
- [Help-bash] pass command to script,
Warlich, Christof <=
- Re: [Help-bash] pass command to script, Warlich, Christof, 2019/04/26
- Re: [Help-bash] pass command to script, Greg Wooledge, 2019/04/26
- Re: [Help-bash] pass command to script, Chet Ramey, 2019/04/26
- Re: [Help-bash] pass command to script, Warlich, Christof, 2019/04/26
- Re: [Help-bash] pass command to script, Chet Ramey, 2019/04/26
- Re: [Help-bash] pass command to script, Warlich, Christof, 2019/04/26
- Re: [Help-bash] pass command to script, Greg Wooledge, 2019/04/26
- Re: [Help-bash] pass command to script, Christof Warlich, 2019/04/26
- Re: [Help-bash] pass command to script, Chet Ramey, 2019/04/26
- Re: [Help-bash] pass command to script, Warlich, Christof, 2019/04/26