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.
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 $month in
3|6|9|12) echo "Yes, time to go on vacations"
;;
*) echo "No, I'd better go on vacations again !"
;;
esac
echo "This is the last line"
I have found this bit of code that nearly does what I want.
Basically 3 input fields, I want to copy t2 to t3 as it's typed but only if t1 contains data AND t3 is empty:
<input type="text" id="t1" />
<input type="text" id="t2" />
<input type="text" id="t3" />
<script> var t2 =... (4 Replies)
I have an xml file which has following code :
<abc-ref>
<abc-name>abc.efg.hij.klm</abc-name>
</abc-ref>
I want to comment this whole section out and I have written the following script : (where "hij" is unique string in the file)
TEMPFILE=replaceYY.tmp
file=hello.xml
sed -n... (6 Replies)
Hi
I'm trying to comment out specific lines from /etc/fstab file, for simplicity I'm trying to use perl one liner but it errors out,
Below is the Perl oneliner I'm using,
perl -wlp -i -e 'BEGIN{$flag=0}if (!/root/) && (!/boot/) && (!/tmpfs/) ) {$flag =1;} elsif (/^$/) {$flag=0} if ($flag)... (2 Replies)
Hi All,
I know we can comment by using "#" .... I want to know... is there any way to comment a whole big script easily....
In a file i need to comment more than 15 lines ........ and check the script and un comment back.
I am learning VI now so its taking lot of time to comment and un... (4 Replies)
Hi All,
I am struggling to get my head around the following issue.
I am having to comment out lines between two delimiters by placing an asterix in position 7 but retain all lines in the file and in the same order.
so for example a file containing:
...
...
DELIM1
...
...
DELIM2... (2 Replies)
Hi
can any body pls help me :
I have a file Which Content is like following:
p3:s1234:powerfail:/usr/sbin/shutdown -y -i5 -g0 >/dev/msglog 2<>/dev/msglog
ca:3:respawn:/opt/GoldWing/currentPM/local/critagt > /dev/msglog 2<>/dev/msglog
ca:3:respawn:/opt/GoldWing/currentPM/local/startcia.sh... (2 Replies)
Hi All
I have a requirement like, where a file gets generated in a particular dir and once the file is ready and available then I want to execute rest of the script, because untill and unless the file exists and is available there is no use of running rest of the commands in that script.
... (5 Replies)
01-02-2008
