Bash script to replace spaces in file names

Question

Can anyone recommend a safe solution to recursively replace spaces with underscores in file and directory names starting from a given root directory? For example,

$ tree
.
|-- a dir
|   `-- file with spaces.txt
`-- b dir
    |-- another file with spaces.txt
    `-- yet another file with spaces.pdf

becomes

$ tree
.
|-- a_dir
|   `-- file_with_spaces.txt
`-- b_dir
    |-- another_file_with_spaces.txt
    `-- yet_another_file_with_spaces.pdf

Edit

Thanks for the answers; they all seem to work. I picked the one by Dennis as the main answer because it seems to me the simplest, even though it takes two steps.

Answer 1

find . -name '* *' -depth \
| while read f ; do mv -i "$f" "$(dirname "$f")/$(basename "$f"|tr ' ' _)" ; done

failed to get it right at first, because I didn't think of directories.

Answer 2

Use rename (aka prename) which is a Perl script which may be on your system already. Do it in two steps:

find -name "* *" -type d | rename 's/ /_/g'    # do the directories first
find -name "* *" -type f | rename 's/ /_/g'

Edit:

Based on Jürgen's answer and able to handle multiple layers of files and directories in a single bound using the "Revision 1.5 1998/12/18 16:16:31 rmb1" version of /usr/bin/rename (a Perl script):

find /tmp/ -depth -name "* *" -execdir rename 's/ /_/g' "{}" \;

Answer 3

A find/rename solution. rename is part of util-linux.

You need to descend depth first, because a whitespace filename can be part of a whitespace directory:

find /tmp/ -depth -name "* *" -execdir rename " " "_" "{}" ";"

Answer 4

bash 4.0

#!/bin/bash
shopt -s globstar
for file in **/*\ *
do 
    mv "$file" "${file// /_}"       
done

Answer 5

Here's a (quite verbose) find -exec solution which writes "file already exists" warnings to stderr:

function trspace() {
   declare dir name bname dname newname replace_char
   [ $# -lt 1 -o $# -gt 2 ] && { echo "usage: trspace dir char"; return 1; }
   dir="${1}"
   replace_char="${2:-_}"
   find "${dir}" -xdev -depth -name $'*[ \t\r\n\v\f]*' -exec bash -c '
      for ((i=1; i<=$#; i++)); do
         name="${@:i:1}"
         dname="${name%/*}"
         bname="${name##*/}"
         newname="${dname}/${bname//[[:space:]]/${0}}"
         if [[ -e "${newname}" ]]; then
            echo "Warning: file already exists: ${newname}" 1>&2
         else
            mv "${name}" "${newname}"
         fi
      done
  ' "${replace_char}" '{}' +
}

trspace rootdir _