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How to execute the rest of the code after commenting multiple lines?


 
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Top Forums Shell Programming and Scripting How to execute the rest of the code after commenting multiple lines?
# 8  
Old 01-02-2008
sorry ..Typing mistake

Quote:
Originally Posted by porter
Your quotes are open.
Hi DRL

This is my mistake.
# 9  
Old 01-02-2008
This should work....

Code:
cat >/dev/null <<IGNORE
asas
das
d
as
das
d
as
IGNORE

# 10  
Old 01-02-2008
Thanks for your reply.

Quote:
Originally Posted by drl
Hi.

A few comments. First, there is a "quoted" string feature in the shells for HERE documents. The use prevents evaluation of everything up to the closing string, including unclosed quotes, variable issues, etc.

Second, ksh does a good job of diagnosing a missing, closing, matching HERE document string -- bash (2 & 3) simply stop.

A ksh example:
Code:
#!/usr/bin/env ksh

# @(#) s1       Demonstrate quick method to render code block inoperable.

set -o nounset
echo

debug=":"
debug="echo"

## The shebang using "env" line is designed for portability and
#  demonstrations. For higher security, use:
#
#  #!/bin/ksh -

## Use local command version for the commands in this demonstration.

echo "(Versions displayed with local utility \"version\")"
version >/dev/null 2>&1 && version ksh

echo
echo " Commands before commented-out block."

: <<'EOF'
garbage
junk
worthless
utterly without merit
" crud inside of double quotes "
' debris inside single quote '
" mess inside unmatched double-quotes
' detritus inside an unmatched single-quote pair
...
and so on.
EOF

echo
echo " Commands after  commented-out block."

echo
echo " Failed block quote due to unmatched HERE stings:"

echo
echo " Commands before commented-out block."

: <<'MISSING'
more junk
OOPS!

echo " Commands after  commented-out block."

exit 0

producing:
Code:
% ./s1

(Versions displayed with local utility "version")
pdksh 5.2.14 99/07/13.2

 Commands before commented-out block.

 Commands after  commented-out block.

 Failed block quote due to unmatched HERE stings:

 Commands before commented-out block.
./s1[53]: here document `MISSING' unclosed

I don't use ksh for reasons of availability (my shebangs almost always use simple "sh"), but in this case ksh is superior ... cheers, drl
Hi DRL,

Thanks for you explanation. But for me it is bit confusing, since i am not aware of the sh. i am using ksh only. Still i will try to understand this code.

Thanks
Yamini.
# 11  
Old 01-02-2008
Thanks Porter

Quote:
Originally Posted by porter
This should work....

Code:
cat >/dev/null <<IGNORE
asas
das
d
as
das
d
as
IGNORE

Hi Porter,

What exactly does this code? I tried and I didnt get anything. Can you pls explain breifly for me?

Thanks
Yamini.
# 12  
Old 01-02-2008
Smilie

You were not supposed to get anything - that was the idea.

Anyway, read this:

SHELLdorado - Shell Tips & Tricks (Programmer)
# 13  
Old 01-02-2008
Hi Yamini,

I still believe there is some confusion in your explanation, because you haven't explained what you are trying to do with your script, give a certain message, execute a command, etc ...

If you only need to ( block) comment lines 5 - 12 out, then that's pretty easy, either use # sign as suggested, or porter's way, or the best way : delete lines 5 - 12 .

It's simply not enough saying script doesn't work. First what are you trying to achieve with your script, besides the point of blocking lines 5 -12 ? Post your script if needed.

I got no problem running happily the following script in my linux machine,( no ksh available, should be the same though ! ).

Code:
#!/bin/bash

month=`date +"%m"`
echo "This is $month month"

echo "
        3,6,9,12 ) Yes, time to go   on vacations 
              
        other months ) No,  I'd better go on vacations again !"
              
echo "Enter month"
read month




case $month in
 3|6|9|12) echo "Yes, time to go on vacations"

    ;;

 *) echo "No, I'd better go on vacations again !"
   
  ;;

 esac

 echo "This is the last line"


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