[BASH] 3 nested loops and command execution confirmation

[gianx80]

Hi to all! I'm a novice to bash programming and I'm studying for an university exam about it. I solved an exercise, but I have a problem.

In my script I have 3 nested loops like these:


cat $FILENAME | while read LINE
do
cd $LINE
ls -p -1 > $TEMPFILE
cat $TEMPFILE | while read FILE
do
cat $TEMPFILE | while read OTHERFILE
do

rm -i $FILE
done
done

done

in the inner loop I have a rm -i command. What is the problem? If I remove the -i option the script works well and files are removed. If I use the -i option (as asked inn the exercise) the script prints to terminal the confirmation messages but it doesn't let me answer yes or no and ends its execution without deleting files.

I've already asked on Italian Ubuntu forums but nobody could help me.

Please help me :(

[ofnuts]

Hi to all! I'm a novice to bash programming and I'm studying for an university exam about it. I solved an exercise, but I have a problem.

In my script I have 3 nested loops like these:


cat $FILENAME | while read LINE
do
cd $LINE
ls -p -1 > $TEMPFILE
cat $TEMPFILE | while read FILE
do
cat $TEMPFILE | while read OTHERFILE
do

rm -i $FILE
done
done

donein the inner loop I have a rm -i command. What is the problem? If I remove the -i option the script works well and files are removed. If I use the -i option (as asked inn the exercise) the script prints to terminal the confirmation messages but it doesn't let me answer yes or no and ends its execution without deleting files.

I've already asked on Italian Ubuntu forums but nobody could help me.

Please help me :(I suspect an interaction between the while read and the input. Did you try something like


for $f in $(cat $otherfile)
do
rm -i $f
done

[sisco311]

@ofnuts

See: BashPitfalls #1 (link in my signature) and http://mywiki.wooledge.org/Quotes


@gianx80

Check out:
http://mywiki.wooledge.org/Quotes
http://mywiki.wooledge.org/ParsingLs
BashFAQ #1 , #20 and #89 (link in my sig)
BashPitfalls #2
and
http://mywiki.wooledge.org/glob

A pipe basically connects the stdout of one process to the stdin of another, effectively piping the data from one process into another.

In our case, | pipes the output of cat into the while loop. By default, both read and rm -i read from stdin. So, read reads the first line from the file, then rm -i reads the rest.

Did you learn about globs? What will */*/* match?

Hmmm, I think I solved your homework...