rm prompt not working when invoked from a piped loop

Question

I am trying to remove files from a directory by pasting their names into a while loop that will simply rm each item from the list of files given to it.

$ sponge | while read file; do echo "rm $file"; rm "$file"; done;
background.bundle.js
964.bundle.js
background.bundle.js.LICENSE.txt
...
META-INF/manifest.mf
META-INF/mozilla.sf
META-INF/mozilla.rsa
^D
rm background.bundle.js
rm: remove regular file ‘background.bundle.js’? $
$

(Notice the ^D at the end)

As shown, after issuing the ^D (end-of-file), the sponge command sends the entire output to the while loop, and rm is invoked for each file separately. However, what happens is that it gets invoked once for background.bundle.js, asks for confirmation, and without allowing me the opportunity to enter anything, the loop exits prematurely. This leaves the prompt character ($) without the necessary newline that should follow it, indicating an abrupt end to the loop.

I am looking to fix this issue without resorting to temporary files. I want to manage file input using exec so that the loop reads from a different input stream, leaving standard input available for rm to read the user’s confirmation. How can I redirect sponge output and read input to a specific file descriptor for this purpose?

Answer 1

If the intention is to remove the files without confirmation when rm is actually an alias or a function similar to this:

alias rm='/bin/rm -i'

Then using the command(1p) utility will bypass the alias/function:

sponge |
while IFS= read -r file; do
    printf "rm %s\n" "$file"
    command rm "$file"
done

If the intention is to force input from the terminal in a subshell, you can use a solution which feels a bit "hacky": reassign only the stdin of rm(1) from /dev/tty (which is the device representing the controlling terminal for the current process):

sponge |
while IFS= read -r file; do
    printf "rm %s\n" "$file"
    rm "$file" </dev/tty       # rm is an alias to '/bin/rm -i'
done

Notes:

1. The recommended idiom for using read(1p) with while is while IFS= read -r ...; do ...; done.
2. printf(1p) is recommended over echo(1p): Why is printf better than echo?.