[gentoo-user] OT: Bash question

[gentoo-user] OT: Bash question

[Anthony E. Caudel]

Is there any way to make "pushd" and "popd" (Bash built-ins) silent?  As
it is, when the execute, the directory is echoed to the output, making
it difficult to use the commands in a script.  For example:

OLD_VER=$(pushd /boot; ls kernel-* | sort | head -1; popd)
echo $OLD_VER
/boot ~ kernel-2.6.22-gentoo-r2 ~

The /boot and the tildes are returned by pushd and popd and mess up the
script.

There doesn't seem to be any options to turn off the echo off and shopt
has nothing in it.

Tony

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Re: [gentoo-user] OT: Bash question

[Dirk Heinrichs]

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Am Donnerstag, 20. September 2007 schrieb ext Anthony E. Caudel:
> Is there any way to make "pushd" and "popd" (Bash built-ins) silent?  As
> it is, when the execute, the directory is echoed to the output, making
> it difficult to use the commands in a script.  For example:

You know you can always redirect output to wherever you want, even 
to /dev/null?

HTH...

	Dirk
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Re: [gentoo-user] OT: Bash question

[Frank Gruellich]

* Anthony E. Caudel <tony.caudel@sbcglobal.net> 20. Sep 07:
> Is there any way to make "pushd" and "popd" (Bash built-ins) silent?
> [snip] For example:
> 
> OLD_VER=$(pushd /boot; ls kernel-* | sort | head -1; popd)
> echo $OLD_VER
> /boot ~ kernel-2.6.22-gentoo-r2 ~

For that exact example... why you bother at all?  $( ) opens a subshell
and cd's in subshells don't interact with parent shell so you could
simply write:

 OLD_VER=$(cd /boot; ls kernel-* | sort | head -1)

or

 OLD_VER=`cd /boot; ls kernel-* | sort | head -1`

if you want to be more compatible.  Or am I missing a point?

HTH, kind regards,
 Frank.
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Re: [gentoo-user] OT: Bash question

[Anthony E. Caudel]

Frank Gruellich wrote:
> * Anthony E. Caudel <tony.caudel@sbcglobal.net> 20. Sep 07:
>   
>> Is there any way to make "pushd" and "popd" (Bash built-ins) silent?
>> [snip] For example:
>>
>> OLD_VER=$(pushd /boot; ls kernel-* | sort | head -1; popd)
>> echo $OLD_VER
>> /boot ~ kernel-2.6.22-gentoo-r2 ~
>>     
>
> For that exact example... why you bother at all?  $( ) opens a subshell
> and cd's in subshells don't interact with parent shell so you could
> simply write:
>
>  OLD_VER=$(cd /boot; ls kernel-* | sort | head -1)
>
> or
>
>  OLD_VER=`cd /boot; ls kernel-* | sort | head -1`
>
> if you want to be more compatible.  Or am I missing a point?
>
> HTH, kind regards,
>  Frank.
>   
Thanks, Frank.  That is the best solution.

Tony

-- 
Those who would give up essential Liberty, to purchase a little temporary Safety, deserve neither Liberty nor Safety.
   -- Benjamin Franklin

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