Using 'find' and 'read' to traverse list, allowing user input inside the loop [Re: cd to folder with spaces - in a script]
MartinG
gronslet at gmail.com
Mon May 25 09:17:40 UTC 2009
On Fri, May 22, 2009 at 10:09 PM, Steven W. Orr <steveo at syslang.net> wrote:
> <snip>
> ii=0
> while read -d $'\000' FOLDERNAME
> do
> savd=$PWD
> cd "$FOLDERNAME"
> ii=$((ii+1))
> cd "$savd"
> done <(find . -type d -print0)
This is all cool, as long as you don't want user input in the middle
of that loop, using another 'read'. In order to do that, one can
redirect the outer pipe to eg. FD 3. The following is a otherwise
meaningless code to illustrate my point:
#!/bin/bash
mypattern='.directory'
mylist=/tmp/mylist.txt
#path="$1"
path=$HOME
while read -u 3 -d $'\000' i; do # see pipe after "done"
echo "Found match: \"$i\""
printf "Add to list ($mylist)? [Y|n] "
read ans
[[ x"$ans" == x"yes" || x"$ans" == x"y" || x"$ans" == x"" ]]
&& (echo "$i" >> $mylist && echo "Added $i") || echo "Skipped, moving
on..."
done 3< <(find $path -iname "$mypattern" -type f -print0)
If I hadn't redirected the "find pipe" to FD 3, the inner "read ans"
would simply read the next matching filename, and fail the user input.
Not sure what would happen if FD 3 for some reason is occupied, maybe
the use of mkfifo is more robust, however I never found a way to get
around FD 3...:
mypipe=`basename $0`-pipe
[ -p $mypipe ] && (rm $mypipe;echo "removed stale pipe")
mkfifo $mypipe
find . -iname "$mypattern" -type f -print0 > $mypipe &
while read -u 3 -d $'\000' i ; do # see pipe after "done"
...
done 3< $mypipe
rm $mypipe
best,
MartinG
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