Scripting fun! :-) (was Re: bash scripting nightmare. ( )

Scripting fun! :-) (was Re: bash scripting nightmare. ( )

[Linda Walsh]

Dave Korn wrote:

>     Hey all, who's any good at bash scripting?
>   
---
   You are doing correctly, mostly. The simplest way to get from
where you are, to where you want to be, is, well think of this:
You have created a "command line" all stuffed into 1 variable, right?
   Ala:  VAR="cvs co -D \"2006-08-10 15:00:00\" -P pci wimedia"
The value of VAR (putting everything between two vertical bars) is:
   |cvs co -D "2006-08-10 15:00:00" -P pci wimedia|
You have a "literal" expression in "VAR", meaning the quotes are stored
as literals and have no special meaning.  If you just try to use "execute"
the literal, the arguments are passed in literally. 

   What you want is for the quotes to regain their special meaning, which
you can do by telling the shell to run it's "eval"uator over the expression
again before executing, as in "eval $VAR".  In line 9 of your code below,
just add an "eval" before the argument.
> 1  #!/bin/bash
> 2  function runCvsCommand()
> 3  {
> 4  # Execute a cvs command, logging appropriately and handling errors.
> 5  echo "CVS: ${1}"
> 6
> 7  # this can take some time
> 8  echo "(cd .;${1})" 
> 9  (cd .; eval ${1}
> 10 RET=$?
Linda

RE: Scripting fun! :-) (was Re: bash scripting nightmare. ( )

[Dave Korn]

On 11 August 2006 00:12, Linda Walsh wrote:

> Dave Korn wrote:
> 
>>     Hey all, who's any good at bash scripting?
>> 
> ---
>    You are doing correctly, mostly. The simplest way to get from
> where you are, to where you want to be, is, well think of this:
> You have created a "command line" all stuffed into 1 variable, right?
>    Ala:  VAR="cvs co -D \"2006-08-10 15:00:00\" -P pci wimedia"
> The value of VAR (putting everything between two vertical bars) is:
>    |cvs co -D "2006-08-10 15:00:00" -P pci wimedia|
> You have a "literal" expression in "VAR", meaning the quotes are stored
> as literals and have no special meaning.  If you just try to use "execute"
> the literal, the arguments are passed in literally.
> 
>    What you want is for the quotes to regain their special meaning, which
> you can do by telling the shell to run it's "eval"uator over the expression
> again before executing, as in "eval $VAR".  In line 9 of your code below,
> just add an "eval" before the argument.

  Thankyou thankyou thank you THANK YOU!

  That made it all seem so clear.  I could see that the quote mark was getting attached to the first word and not keeping the two words as one arg, but I didn't know what it means or what to do with it.  Eval'ing it worked perfectly, just like you said.  Thanks for saving my sanity!

    cheers,
      DaveK
-- 
Can't think of a witty .sigline today....

RE: Scripting fun! :-) (was Re: bash scripting nightmare. ( )

[Igor Peshansky]

On Fri, 11 Aug 2006, Dave Korn wrote:

> On 11 August 2006 00:12, Linda Walsh wrote:
>
> > Dave Korn wrote:
> >
> >>     Hey all, who's any good at bash scripting?
> >>
> > ---
> >    You are doing correctly, mostly. The simplest way to get from
> > where you are, to where you want to be, is, well think of this:
> > You have created a "command line" all stuffed into 1 variable, right?
> >    Ala:  VAR="cvs co -D \"2006-08-10 15:00:00\" -P pci wimedia"
> > The value of VAR (putting everything between two vertical bars) is:
> >    |cvs co -D "2006-08-10 15:00:00" -P pci wimedia|
> > You have a "literal" expression in "VAR", meaning the quotes are stored
> > as literals and have no special meaning.  If you just try to use "execute"
> > the literal, the arguments are passed in literally.
> >
> >    What you want is for the quotes to regain their special meaning, which
> > you can do by telling the shell to run it's "eval"uator over the expression
> > again before executing, as in "eval $VAR".  In line 9 of your code below,
> > just add an "eval" before the argument.
>
>   Thankyou thankyou thank you THANK YOU!
>
>   That made it all seem so clear.  I could see that the quote mark was
> getting attached to the first word and not keeping the two words as one
> arg, but I didn't know what it means or what to do with it.  Eval'ing it
> worked perfectly, just like you said.  Thanks for saving my sanity!

Not to sound defensive, but did you happen to see
<http://cygwin.com/ml/cygwin-talk/2006-q3/msg00138.html> from yesterday?
Just curious...
	Igor
-- 
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      |\      _,,,---,,_	    pechtcha@cs.nyu.edu | igor@watson.ibm.com
ZZZzz /,`.-'`'    -.  ;-;;,_		Igor Peshansky, Ph.D. (name changed!)
     |,4-  ) )-,_. ,\ (  `'-'		old name: Igor Pechtchanski
    '---''(_/--'  `-'\_) fL	a.k.a JaguaR-R-R-r-r-r-.-.-.  Meow!

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"But no -- you are no fool; you call yourself a fool, there's proof enough in
that!" -- Rostand, "Cyrano de Bergerac"

RE: Scripting fun! :-) (was Re: bash scripting nightmare. ( )

[Dave Korn]

On 11 August 2006 16:14, Igor Peshansky wrote:

> On Fri, 11 Aug 2006, Dave Korn wrote:
> 
>> On 11 August 2006 00:12, Linda Walsh wrote:
>> 
>>> Dave Korn wrote:
>>> 
>>>>     Hey all, who's any good at bash scripting?
>>>> 
>>> ---
>>>    You are doing correctly, mostly. The simplest way to get from
>>> where you are, to where you want to be, is, well think of this:
>>> You have created a "command line" all stuffed into 1 variable, right?
>>>    Ala:  VAR="cvs co -D \"2006-08-10 15:00:00\" -P pci wimedia"
>>> The value of VAR (putting everything between two vertical bars) is:
>>>    |cvs co -D "2006-08-10 15:00:00" -P pci wimedia|
>>> You have a "literal" expression in "VAR", meaning the quotes are stored
>>> as literals and have no special meaning.  If you just try to use "execute"
>>> the literal, the arguments are passed in literally.
>>> 
>>>    What you want is for the quotes to regain their special meaning, which
>>> you can do by telling the shell to run it's "eval"uator over the
>>> expression again before executing, as in "eval $VAR".  In line 9 of your
>>> code below, just add an "eval" before the argument.
>> 
>>   Thankyou thankyou thank you THANK YOU!
>> 
>>   That made it all seem so clear.  I could see that the quote mark was
>> getting attached to the first word and not keeping the two words as one
>> arg, but I didn't know what it means or what to do with it.  Eval'ing it
>> worked perfectly, just like you said.  Thanks for saving my sanity!
> 
> Not to sound defensive, but did you happen to see
> <http://cygwin.com/ml/cygwin-talk/2006-q3/msg00138.html> from yesterday?
> Just curious...
> 	Igor

  Yep, but I was reading my mail out-of-order.  However, just to show there's
no favouritism going on here,

Thankyou thankyou thank you THANK YOU IGOR!

    cheers,
      DaveK
-- 
Can't think of a witty .sigline today....

bash scripting nightmare.

[Dave Korn]

    Hey all, who's any good at bash scripting?

  I've been trying for two-and-a-half hours now to make a fairly simple shell
script work, and I've been through every imaginable combination of quoting,
and nothing I've tried works.  The bash FAQ doesn't have anything to say on
the matter, nor could I figure it out from the Advanced Bash-Scripting Guide.

  I'm not a proud man, so I don't mind begging for help.  The trouble is that
I want to:

a) declare a variable which contains the date in ANSI format, then 
b) concatenate that variable and a few others into another variable, then
c) pass that other variable to a function, then finally
d) invoke the command line specified in the variable within the function.

  Sounds easy, you think?  Not quite.  There's a catch: the date string
contains a space in it.  And I can't find any way at all to get that date
string passed to the command line from within the function without that space
breaking things totally.  If I don't try and quote it, the time part of the
datestamp is taken as a separate command line argument and cvs doesn't
understand it.  If I do try and quote it, bash mangles the variable into
gibberish.  Let me demonstrate:


--------------------------------<snip>--------------------------------
#!/bin/bash
function runCvsCommand()
{
# Execute a cvs command, logging appropriately and handling errors.
echo "CVS: ${1}"

# this can take some time
echo "(cd .; ${1})"
(cd .; ${1})
RET=$?

if [ $RET -ne 0 ]
then
	echo "CAN'T '$1' STATUS $RET"
	exit 12
fi

echo "CHECKOUT $1 TO DIRECTORY $NEWDIR OK"
}

CVSCOM="cvs co"
CVSDATE="`date +'%Y-%m-%d %H:00:00'`"

CVSOPTS="-D \"${CVSDATE}\" -P" # CVSDATE has a space so must be quoted.

CVSFILES1="ieee usb"
CVSFILES2="pci wimedia"

CVSCMD1="${CVSCOM} ${CVSOPTS} ${CVSFILES1}"
CVSCMD2="${CVSCOM} ${CVSOPTS} ${CVSFILES2}"

echo "OK... CMD1 IS ${CVSCMD1} "
runCvsCommand "${CVSCMD1}"
echo "OK;; CMD2 IS ${CVSCMD2} "
runCvsCommand "${CVSCMD2}"
--------------------------------<snip>--------------------------------

  And here's what I see:

--------------------------------<snip>--------------------------------
OK... CMD1 IS cvs co -D "2006-08-10 18:00:00" -P ieee usb
CVS: cvs co -D "2006-08-10 18:00:00" -P ieee usb
(cd .; cvs co -D "2006-08-10 18:00:00" -P ieee usb)
cvs [checkout aborted]: Can't parse date/time: "2006-08-10
CAN'T 'cvs co -D "2006-08-10 18:00:00" -P ieee usb' STATUS 1
--------------------------------<snip>--------------------------------

  If I remove the escapes on the quotes in the CVSOPTS assignment, or remove
the quotes altogether, I get

--------------------------------<snip>--------------------------------
OK... CMD1 IS cvs co -D 2006-08-10 18:00:00 -P ieee usb
CVS: cvs co -D 2006-08-10 18:00:00 -P ieee usb
(cd .; cvs co -D 2006-08-10 18:00:00 -P ieee usb)
cvs server: cannot find module `18:00:00' - ignored
cvs server: cannot find module `-P' - ignored
cvs server: cannot find module `ieee' - ignored
cvs server: cannot find module `usb' - ignored
cvs [checkout aborted]: cannot expand modules
CAN'T 'cvs co -D 2006-08-10 18:00:00 -P ieee usb' STATUS 1
--------------------------------<snip>--------------------------------

  I've tried about a million combinations now and I'm getting nowhere.  I even
tried replacing the in the date with "__space__" and using "${1//__space__/ }"
in the function invocation but that didn't help either.

  I'm just not getting it.  Can anyone explain it to me?



    cheers,
      DaveK
-- 
Can't think of a witty .sigline today....

Scripting fun! :-) (was Re: bash scripting nightmare. ( )

[Linda A. Walsh]

Dave Korn wrote:
>     Hey all, who's any good at bash scripting?
>   
---
    You are doing correctly, mostly. The simplest way to get from
where you are, to where you want to be, is, well think of this:
You have created a "command line" all stuffed into 1 variable, right?
    Ala:  VAR="cvs co -D \"2006-08-10 15:00:00\" -P pci wimedia"
The value of VAR (putting everything between two vertical bars) is:
    |cvs co -D "2006-08-10 15:00:00" -P pci wimedia|
You have a "literal" expression in "VAR", meaning the quotes are stored
as literals and have no special meaning.  If you just try to use "execute"
the literal, the arguments are passed in literally. 

    What you want is for the quotes to regain their special meaning, which
you can do by telling the shell to run it's "eval"uator over the expression
again before executing, as in "eval $VAR".  In line 9 of your code below,
just add an "eval" before the argument.
> 1  #!/bin/bash
> 2  function runCvsCommand()
> 3  {
> 4  # Execute a cvs command, logging appropriately and handling errors.
> 5  echo "CVS: ${1}"
> 6
> 7  # this can take some time
> 8  echo "(cd .;${1})" 
> 9  (cd .; eval ${1}
> 10 RET=$?
Linda