variable redirect messing up a sed command.

Shell Programming and Scripting
1

Not sure if that title is decent, but here we go. I'm running this string of commands:

qstat -f $1 | sed 's/^[ \t]*//' | sed -n -e ":a" -e "$ s/\n//gp;N;b a" | sed 's/\\,/,/' | awk -F"PBS_O_WORKDIR=" '{print $2}' | awk -F",PBS_O_SYSTEM" '{print $1}'

In case you're curious is takes the output of a PBS queue, removes all the leading spaces, removes all the linebreaks, removes the backslash escape character in front of any commas, then grabs the output between two strings, effectively extracting a variable from a large mess of output from PBS.

When I run that, it works just fine, all steps work perfectly. However, when I direct the output into a variable, the sed command to remove the backslash fails.

So, I simplified the problem:

echo "Hello\,World" | sed 's/\\,/,/' --> "Hello,World"
var=`echo "Hello\,World" | sed 's/\\,/,/'`; echo $var --> "Hello\,World"

any thoughts?

2

"Cascading backslashes" a.k.a "Leaning toothpicks"!:wink:

var=`echo "Hello\,World" | sed 's/\\\,/,/'`; echo $var --> "Hello,World"

seems to work!

It's because the backticks are spawning another subshell, but the original backslashes have already been interpreted by the first one.

3

this simple tr will do that

echo "Hello\,World"|tr -d '\\'
4

Or

var=$(echo "Hello\,world" | sed 's/\\,/,/g'); echo $var

-Devaraj Takhellambam