I have a bash script that can get passed any number of different
parameters.  At one point, I need to test if a particular parameter
has been passed.  For example, the script could be called by "myscript
A B C", or it could be called by "myscript B C A".  All I care about
is if "B" was passed.

I know I can do this with a loop, checking each parameter, but I was
wondering if it can be done without a loop, and preferably without
calling an external program (like awk).  Any ideas?

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On 4 Oct 2004 16:01:38 -0700, Timur Tabi wrote:
> I have a bash script that can get passed any number of different
> parameters.  At one point, I need to test if a particular parameter
> has been passed.  For example, the script could be called by "myscript
> A B C", or it could be called by "myscript B C A".  All I care about
> is if "B" was passed.
>
> I know I can do this with a loop, checking each parameter, but I was
> wondering if it can be done without a loop, and preferably without
> calling an external program (like awk).  Any ideas?

use _if_ statements

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On Mon, 04 Oct 2004 16:01:38 -0700, Timur Tabi wrote:

> I have a bash script that can get passed any number of different
> parameters.  At one point, I need to test if a particular parameter has
> been passed.  For example, the script could be called by "myscript A B C",
> or it could be called by "myscript B C A".  All I care about is if "B" was
> passed.
>
> I know I can do this with a loop, checking each parameter, but I was
> wondering if it can be done without a loop, and preferably without calling
> an external program (like awk).  Any ideas?

Here is something that works if all parameters are single characters. Only
lightly tested -- may have bugs or make unwarranted assumptions!

=================================
#!/bin/bash

p="C"	# variable p is set to parameter to look for

if [ "${*/$p/}" != "$*" ] ; then
echo "$p seen"
else
echo "$p not seen"
fi
=================================

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On 2004-10-05, Bob <bob@dont.spam.me> wrote:
> Here is something that works if all parameters are single characters. Only
> lightly tested -- may have bugs or make unwarranted assumptions!
>
> =================================
> #!/bin/bash
>
> p="C"	# variable p is set to parameter to look for
>
> if [ "${*/$p/}" != "$*" ] ; then
>         echo "$p seen"
> else
>         echo "$p not seen"
> fi
> =================================

For non-single characters, following the same idea, one could do:

p="theOption"	# variable p is set to parameter to look for

if [ "${*/ $p /}" != "$*" ] ; then
echo "$p seen"
else
echo "$p not seen"
fi

--Seb

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Timur Tabi <nospam_timur@tabi.org> wrote:
> I have a bash script that can get passed any number of different
> parameters.  At one point, I need to test if a particular parameter
> has been passed.  For example, the script could be called by "myscript
> A B C", or it could be called by "myscript B C A".  All I care about
> is if "B" was passed.
>
> I know I can do this with a loop, checking each parameter, but I was
> wondering if it can be done without a loop, and preferably without
> calling an external program (like awk).  Any ideas?

Not in standard shell.  With my patch to Bash shell,
${*|/B}
${@|/B}
will return positional parameters matching glob pattern 'B'.

Ref:
http://freshmeat.net/projects/bashdiff/
--
William Park <opengeometry@yahoo.ca>
Open Geometry Consulting, Toronto, Canada

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On Tue, 05 Oct 2004 02:10:27 +0000, Seb wrote:

> On 2004-10-05, Bob <bob@dont.spam.me> wrote: 
>
> For non-single characters, following the same idea, one could do:
>
> p="theOption"	# variable p is set to parameter to look for
>
> if [ "${*/ $p /}" != "$*" ] ; then
>   echo "$p seen"
> else
>   echo "$p not seen"
> fi
>
> --Seb

Need to account for the optoin being first or last:

p="theOPtion"

opts=" $* "
if [ "${opts/ $p /}" != "$opts" ] ; then
<the rest as above>

Warning *totally* untested!

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Timur Tabi wrote:
> I have a bash script that can get passed any number of different
> parameters.  At one point, I need to test if a particular parameter
> has been passed.  For example, the script could be called by "myscript
> A B C", or it could be called by "myscript B C A".  All I care about
> is if "B" was passed.
>
> I know I can do this with a loop, checking each parameter, but I was
> wondering if it can be done without a loop, and preferably without
> calling an external program (like awk).  Any ideas?

This will work if all your parameters are single-character and take no
arguments that might contain a "B":

case $* in
*B* )	echo "Eureka!" ;;
* )	echo "boo hoo..." ;;
esac

Regards,

Ed.

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2004-10-04, 22:15(-05), Ed Morton:
[...]
> case $* in
> 	*B* )	echo "Eureka!" ;;
> 	* )	echo "boo hoo..." ;;
> esac
[...]

That tests wether the concatenation (with spaces unless IFS was
modified) of the arguments contains "B", not wether there's a
"B" amongst the arguments

With zsh:

if (( $+argv[(r)B] )); then
echo "Eureka!"
else
echo "boo hoo..."
fi

There's no equivalent with bash, unless you're ready to suppose
that one particular character is not present in the arguments:

If it's "|":

IFS="|"
case "|$*|" in
*"|B|"*) echo yes;;
*) echo no;;
esac

--
Stephane

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On 4 Oct 2004 16:01:38 -0700, Timur Tabi
<nospam_timur@tabi.org> wrote:
> I have a bash script that can get passed any number of different
> parameters.  At one point, I need to test if a particular parameter
> has been passed.  For example, the script could be called by "myscript
> A B C", or it could be called by "myscript B C A".  All I care about
> is if "B" was passed.
>
> I know I can do this with a loop, checking each parameter, but I was
> wondering if it can be done without a loop, and preferably without
> calling an external program (like awk).  Any ideas?

case "$*" in
B *|* B *|* B)  echo "script has B" ;;
esac

--
System Events
=-=-=-=-=-=-=
Sep 16 03:31:11 don kernel: lp0 on fire

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2004-10-5, 07:15(-04), Bill Marcum:
[...]
> case "$*" in
>  B *|* B *|* B)  echo "script has B" ;;
> esac

~$ case "$*" in
case>  B *|* B *|* B)  echo "script has B" ;;
zsh: parse error near `*'
bash: syntax error near unexpected token `*'
esac> ksh: syntax error: `*' unexpected
esac> syntax error: `*' unexpected


Should be:

case "$*" in
B\ *|*\ B\ *|*\ B)  echo "script has B" ;;
esac

But that works only for Bourne shell or with POSIX shells if IFS
is unset or starts with " ".

It's not reliable if arguments may contain spaces.

It can be shortened as:

case " $* " in
*" B "*)  echo "script has B" ;;
esac

Actually, with bash and ksh93 (not zsh), you can do it as:

IFS=,
case ",${*//,/}," in
*,B,*) echo script has B;;
esac

Of course, that doesn't work if instead of "B", you have a
string with commas in it (but you could use an other character
then as first character of IFS).

I guess you shouldn't rely on that behavior as it's not the
behavior one would expect (at least by Bourne standard, $* is
supposed to be a normal parameter whose value is the
concatenation of the arguments with first character of IFS
inbetween, so that ${*//,/} shouldn't contain any ",").

--
Stephane

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