Re: [Server-devel] Fixing bash script bogosity - help?
On Mon, 2009-04-27 at 22:37 +0200, Martin Langhoff wrote: Hi all, I have a simple shell scripting problem :-) you'll find attached a shell script that ships with ejabberd. It is a fairly straightforward bit of code, and allows us to control bits of the ejabberd internals with a nice cli interface. (Feel free to skip the start / stop bits of the code, I'm fighting with the ctrl function.) The problem it has is that the parameters are passed to a bash or runas invocation -- at which point the quoting is a mess. Currently I am working around it in the caller by doing some stupid nested-quoting. But this should be easy to cure -- if anyone knows a bit more bash (or portable shell!) than me :-) A minimal exposition of the problem is as follows: $ cat sample.sh #!/bin/bash -x # in the script, the CMD is built up as a string CMD=touch $@ http://mywiki.wooledge.org/BashFAQ/050 -- Ignacio Vazquez-Abrams ivazquez...@gmail.com signature.asc Description: This is a digitally signed message part ___ Server-devel mailing list Server-devel@lists.laptop.org http://lists.laptop.org/listinfo/server-devel
Re: [Server-devel] Fixing bash script bogosity - help?
On Tue, 2009-04-28 at 11:17 +0200, Martin Langhoff wrote:
On Tue, Apr 28, 2009 at 9:27 AM, Ignacio Vazquez-Abrams
ivazquez...@gmail.com wrote:
# in the script, the CMD is built up as a string
CMD=touch $@
http://mywiki.wooledge.org/BashFAQ/050
That repeats what we know already. The thing is that we are building
the command as a string for runuser, which wants it as a parameter.
It is an interesting question, I think. Can you make my sample script
work, while still handling $CMD as a string? Some sample input for the
challenge:
No, I can't. The first section explains that it can't be done
*precisely* for the same reason you've already discovered.
But if you're willing to let go of this futile quest to keep $CMD a
string then you'll find that it can be done:
#! /bin/bash
CMD=(touch $@)
bash -c ${c...@]}
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Re: [Server-devel] Fixing bash script bogosity - help?
On Tue, Apr 28, 2009 at 1:01 PM, Ignacio Vazquez-Abrams
ivazquez...@gmail.com wrote:
Which part of the following doesn't work?
Just test your minimal 3 line script with the example input I've given
you. It breaks:
# cat sample.sh
#! /bin/bash
CMD=(touch $@)
bash -c ${c...@]}
# ./sample.sh this is file one this is file two file
# bash -x ./sample.sh this is file one this is file two file \ f
+ CMD=(touch $@)
+ bash -c touch 'this is file one' 'this is file two' 'file f'
touch: missing file operand
Try `touch --help' for more information.
Bash (line runuser) expects a line of shell, quoted/escaped
appropriately, as a single string param -c
*that* is the challenge.
m
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Re: [Server-devel] Fixing bash script bogosity - help?
bert wrote:
On 28.04.2009, at 13:37, Martin Langhoff wrote:
On Tue, Apr 28, 2009 at 1:19 PM, Ignacio Vazquez-Abrams
ivazquez...@gmail.com wrote:
Ah, I see now.
Try this:
bash -c 'touch $@' ${c...@]}
Riiight, that works better... but
Or in the case of the full script:
bash -c $ERL' $@' ${erl_comma...@]}
...it doesn't work for runuser -- which is the real target. Runuser
looks at the added params after -c and tries to parse them. There
doesn't seem to be any support for passing parameters.
hm.
Maybe you should use su directly instead of runuser?
won't that have the same problem? it still wants a command
passed via a -c STRING convention.
i think this is somewhat intractable, and any time spent on it
would be better spent creating a patch to runuser that lets it
take its command as strace does, or as xterm does with -e, which
avoids the vector-string-vector translations which are the real
issue.
paul
=-
paul fox, p...@laptop.org
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Re: [Server-devel] Fixing bash script bogosity - help?
On Tue, 2009-04-28 at 12:38 +0200, Martin Langhoff wrote:
On Tue, Apr 28, 2009 at 12:03 PM, Ignacio Vazquez-Abrams
ivazquez...@gmail.com wrote:
But if you're willing to let go of this futile quest to keep $CMD a
string then you'll find that it can be done:
Your example doesn't work. I don't care about keeping $CMD as a
string, I think you are misunderstanding the problem. We need to build
it as a string to provide it as a single parameter value. This is
because we want to run the command with all properly escaped params
under runuser.
Which part of the following doesn't work?
ctl()
{
ERL_COMMAND=(
$ERL
$NAME ejabberctl
-noinput
-pa $EJABBER_EBIN
-s ejabber_ctl -extra $ERLANG_NODE $@
)
W=`whoami`
if [ $W != ejabberd ]; then
/sbin/runuser -s /bin/bash - ejabberd -c ${erl_comma...@]}
result=$?
else
bash -c ${erl_comma...@]}
result=$?
fi
# replace remainder of function here
}
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Re: [Server-devel] Fixing bash script bogosity - help?
On Tue, Apr 28, 2009 at 9:27 AM, Ignacio Vazquez-Abrams ivazquez...@gmail.com wrote: # in the script, the CMD is built up as a string CMD=touch $@ http://mywiki.wooledge.org/BashFAQ/050 That repeats what we know already. The thing is that we are building the command as a string for runuser, which wants it as a parameter. It is an interesting question, I think. Can you make my sample script work, while still handling $CMD as a string? Some sample input for the challenge: $ ./sample.sh ./sample.sh this is file one this is file two file with doublequotes \ in it cheers, m -- martin.langh...@gmail.com mar...@laptop.org -- School Server Architect - ask interesting questions - don't get distracted with shiny stuff - working code first - http://wiki.laptop.org/go/User:Martinlanghoff ___ Server-devel mailing list Server-devel@lists.laptop.org http://lists.laptop.org/listinfo/server-devel
Re: [Server-devel] Fixing bash script bogosity - help?
hi martin -- I have a simple shell scripting problem :-) you'll find attached a shell script that ships with ejabberd. It is a fairly straightforward bit of code, and allows us to control bits of the ejabberd internals with a nice cli interface. (Feel free to skip the start / stop bits of the code, I'm fighting with the ctrl function.) The problem it has is that the parameters are passed to a bash or runas invocation -- at which point the quoting is a mess. Currently I am working around it in the caller by doing some stupid nested-quoting. But this should be easy to cure -- if anyone knows a bit more bash (or portable shell!) than me :-) A minimal exposition of the problem is as follows: $ cat sample.sh #!/bin/bash -x # in the script, the CMD is built up as a string CMD=touch $@ # in practice we somtimes use /sbin/runuser -c # and other times plain bash -c bash -c $CMD first, you want to preserve the original quoting of the args by using $@. it must look just like that. second, you don't need the bash -c there. just run $CMD directly. so, the invocation you want is: CMD=touch $CMD $@ in your original script looks like this ERL_COMMAND=$ERL \ $NAME ejabberdctl \ -noinput \ -pa $EJABBERD_EBIN \ -s ejabberd_ctl -extra $ERLANG_NODE $@ \ W=`whoami` if [ $W != ejabberd ]; then /sbin/runuser -s /bin/bash - ejabberd -c $ERL_COMMAND result=$? else bash -c $ERL_COMMAND result=$? fi a) remove $@ from the ERL_COMMAND definition b) change the bash -c line to be: $ERL_COMMAND $@ c) to fix the runuser invocation (assuming it's broken, and i guess it probably is), i think will be trickier. i'm sure we can fix it though. how's this so far? paul =- paul fox, p...@laptop.org ___ Server-devel mailing list Server-devel@lists.laptop.org http://lists.laptop.org/listinfo/server-devel
Re: [Server-devel] Fixing bash script bogosity - help?
I'm no maven, but the last time I was dealing with quoting issues with $* expansion I had found this article helpful: http://www.ibm.com/developerworks/library/l-bash-parameters.html?ca=drs- Sean On Mon, Apr 27, 2009 at 10:37 PM, Martin Langhoff martin.langh...@gmail.com wrote: Hi all, I have a simple shell scripting problem :-) you'll find attached a shell script that ships with ejabberd. It is a fairly straightforward bit of code, and allows us to control bits of the ejabberd internals with a nice cli interface. (Feel free to skip the start / stop bits of the code, I'm fighting with the ctrl function.) The problem it has is that the parameters are passed to a bash or runas invocation -- at which point the quoting is a mess. Currently I am working around it in the caller by doing some stupid nested-quoting. But this should be easy to cure -- if anyone knows a bit more bash (or portable shell!) than me :-) A minimal exposition of the problem is as follows: $ cat sample.sh #!/bin/bash -x # in the script, the CMD is built up as a string CMD=touch $@ # in practice we somtimes use /sbin/runuser -c # and other times plain bash -c bash -c $CMD # this invokation does the wrong thing - $ ./sample.sh ./sample.sh this is file one this is file two # the ugly workaround is ./sample.sh 'this is file one' 'this is file two' Any hints that don't involve a rewrite? cheers, martin-who's-easily-stumped-with-shell-backwardnesss -- martin.langh...@gmail.com mar...@laptop.org -- School Server Architect - ask interesting questions - don't get distracted with shiny stuff - working code first - http://wiki.laptop.org/go/User:Martinlanghoff ___ Server-devel mailing list Server-devel@lists.laptop.org http://lists.laptop.org/listinfo/server-devel ___ Server-devel mailing list Server-devel@lists.laptop.org http://lists.laptop.org/listinfo/server-devel
