Shell Programming and Scripting

greetings,

not being much of a perl user i'm having an issue when trying to assign a value to a variable using the following:

Code:

$StatusRawString=`grep -F -e \'time...\' $Glstat | tail -n 1`;

when i execute the perl script i'm using the -w option to get some useful info on how the script is doing (or not doing) and i get the following output:

Code:

sh: -c: line 1: syntax error near unexpected token `|'
sh: -c: line 1: ` | tail -n 1'

it clearly doesn't like my syntax and and appears that it's executing the "| tail -n 1" on its own command line. i've tried dbl quotes and escapes and haven't found the magic combo. i am executing this perl script from a bash shell fyi. any suggestions?

thanx in advance.

A few tips..

First, it's not perl that's not liking your syntax -- it's sh.

Which means that, yes, perl is running a new shell each and every time you use backticks.

So by embedding lots of shell code in backticks, you are running dozens of shells instead of one single one.

As for what's upsetting sh here... I'm guessing perl is shoving the string into sh inside single-quotes, which you are ending early with your own single quotes. Try unescaped double quotes.

Code:

$StatusRawString=`grep -F -e "time..." $Glstat | tail -n 1`;

greetings,

i understand that it's the shell that dislikes what it's getting from the perl script. i just don't know how to get perl to give the shell what i'm obviously trying to pass to it. the escaped dbl quotes yielded the same result. if this helps, the line below works but i'm trying to eliminate the su and rsh and simply gettin what i need from the now nfs mounted filesystem where $Glstat lives:

Code:

$StatusRawString=`su $USER -c "rsh $HeadNode \\\"grep -F -e 'time...' $Glstat\\\" | tail -n 1"`;

Have you tried using Perl's Grep function?

Code:

grep - perldoc.perl.org

Is $glstat a file or application?

$Glstat is a large output file from a running process. unfortunately the line i'm looking for is in it many times, hence the need to tail -n 1 to grab the last occurrence of it. fyi, i managed to define the $Glstat variable as follows and got away with it:

Code:

$Glstat=`find $LsfTmp -name \"\*glstat\*\" | tail -n 1 2> /dev/null`;

thanks.

---------- Post updated 03-21-13 at 10:09 AM ---------- Previous update was 03-20-13 at 11:56 AM ----------

---------- Post updated at 10:10 AM ---------- Previous update was at 10:09 AM ----------

mystery solved!

i found out we had a perl developer here so i posed the question to him. he said that his first thought was that "$Glstat" had a newline. so he told me me drop the code below right after setting it:

Code:

chomp($Glstat);