Script variable issue..

[ksauerwald]

I'm trying to write a quick script to copy a file then rename parts of it using a passed in argument.

so PREFIX is seg to KEVIN lets say.. then I use this command..

#FIX PROCESS V
DEST_NAME=$CURR_DIR/process_{$PREFIX}.cpp

cp $CURR_DIR/process_voice_to_text.cpp $DEST_NAME

perl -pi -e 's/process_voice_to_text/process_${PREFIX}/g' DEST_NAME

now the copy works fine.. but when I try to use ${PREFIX} in the statement it ends up just using "process_" for the perl replace.

doesnt resolve it.. I also tried to do this..

COMMAND="'s/merge_normal_documents/merge_normal_documents_${PREFIX}/g'"
print $COMMAND

perl -pi -e $COMMAND $DEST_NAME

that doesnt work either.. the print comes out ok

(r) [rad-ri_PRD] /SMSCLN/prd/src/res>  BuildNewV2t.sh KEVIN

's/merge_normal_documents/merge_normal_documents_KEVIN/g'

but when it runs it.. it does nothing.. so I must be missing something.. anyone try to do that same thing with an outcome ?

[burschik]

Learn to use quotation marks properly. Compare

echo "$HOME"

with

echo '$HOME'

[ksauerwald]

I looked at your advice and got no where.. so I tried a test..

I made a file

[rad-ri_PRD] /SMSCLN/prd/src/res> vi test.txt

CHANGE1
CHANGE2
CHANGE3
CHANGE4

wrote a new script with lots of options

typeset PREFIX

PREFIX="SOMETHING NEW"

perl -pi -e 's/CHANGE1/CHANGED_TO_"${PREFIX}"/g' test.txt
echo "1"
perl -pi -e 's/CHANGE2/CHANGED_TO_'${PREFIX}'/g' test.txt
echo "2"
perl -pi -e 's/CHANGE3/CHANGED_TO_${PREFIX}/g' test.txt
echo "3"
perl -pi -e 's/CHANGE4/CHANGED_TO_$PREFIX/g' test.txt
echo "4"

had an error on number two.. go figure

here is the end result of the text file..

CHANGED_TO_""
CHANGE2
CHANGED_TO_
CHANGED_TO_

so unless I'm missing something.. I have no clue how to format that perl command so it resolves the $PREFIX and will do the command correctly...

any ideas ?

[burschik]

Single quotes inhibit parameter expansion, double quotes do not. Try this:

perl -pi -e "s/CHANGE1/CHANGED_TO_${PREFIX}/g" test.txt

Use "set -x" to improve your understanding of what the shell does.

[ksauerwald]

See I thought the perl script command would need the single quote to work.. I never did a perl script in my life.. and only wrote like 5 shell ones..

that worked.. thanks..

[burschik]

I never did a perl script in my life..

That is entirely irrelevant. We are talking about preventing the shell from doing parameter expansion (or other types of expansion, for that matter). For example:

echo $$

prints the PID of your shell.

perl -e "print $$;"

also prints the PID of your shell because the shell replaces the string "$$" with its own PID before handing that string to perl. So what perl actually gets is "print 1234;" (or some other random number). On the other hand

perl -e 'print $$;'

will print the PID of the perl interpreter, because the single quotes prevent the shell from replacing "$$" with its own PID.