Krdytkyu

I would like to rename a series of files named this way

name (10).ext

name (11).ext

...

to

name_10.ext

name_11.ext

...

This one-liner works:

$ for i in name (* ; do echo "$i" | sed -e 's! (([0-9]{2}))!_1!' ; done

name_10.ext

name_11.ext

...

But this one doesn't:

$ for i in name (* ; do mv "$i" "$(echo "$i" | sed -e 's! (([0-9]{2}))!_1!')" ; done

bash: !_1!': event not found

Why? How to avoid this?

Using

$ bash --version

GNU bash, versione 4.3.48(1)-release (x86_64-pc-linux-gnu)

on Ubuntu 18.04.

While in this similar question a simple case with ! is shown, here a ! just inside single quotes is considered and compared to a ! inside single quotes, inside double quotes. As pointed out in the comments, Bash behaves in a different way in these two cases. This is about Bash version 4.3.48(1); this problem seems instead to be no more present in 4.4.12(1) (it is however recommended to avoid this one-liner, because the Bash version may be unknown in some cases).

As suggested in the Kusalananda answer, if the sed delimiter ! is replaced with #,

$ for i in name (* ; do mv "$i" "$(echo "$i" | sed -e 's# (([0-9]{2}))#_1#')" ; done

this problem does not arise at all.

When used in an interactive shell, the ! may initiate history expansion (not an issue in scripts).

The solution is to use another delimiter than ! in the sed expression.

An alternative bash loop:

for name in "name ("*").ext"; do

    if [[ "$name" =~ (.*)" ("([^)]+)").ext" ]]; then

        newname="${BASH_REMATCH[1]}_${BASH_REMATCH[2]}.ext"

        printf 'Would move %s to %sn' "$name" "$newname"

        # mv -i "$name" "$newname"

    fi

done

You can use Larry Wall's rename command (rename package in Debian, prename in RedHat): it uses the (much easier IMHO) Perl regex syntax, and will iterate the file args (no need to code a loop):

rename 's/ (d+)/_$1/' name *

If you know the exact range, you can rename the files like this:

for i in {10..99}; do mv "name ($i).ext" "name_$i.ext"; done

Or, if you want to be POSIX-pedantic:

for i in `seq 10 99`; do mv "name ($i).ext" "name_$i.ext"; done