How to replace spaces in file names using a bash script

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

I use:

for f in *\ *; do mv "$f" "${f// /_}"; done

Though it's not recursive, it's quite fast and simple. I'm sure someone here could update it to be recursive.

The ${f// /_} part utilizes bash's parameter expansion mechanism to replace a pattern within a parameter with supplied string. The relevant syntax is ${parameter/pattern/string}. See: https://www.gnu.org/software/bash/manual/html_node/Shell-Parameter-Expansion.html or http://wiki.bash-hackers.org/syntax/pe .

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'

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' "{}" \;

find . -depth -name '* *' \
| while IFS= read -r 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.

you can use detox by Doug Harple

detox -r <folder>

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 " " "_" "{}" ";"

you can use this:

find . -depth -name '* *' | while read fname 

do
        new_fname=`echo $fname | tr " " "_"`

        if [ -e $new_fname ]
        then
                echo "File $new_fname already exists. Not replacing $fname"
        else
                echo "Creating new file $new_fname to replace $fname"
                mv "$fname" $new_fname
        fi
done

bash 4.0

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

Recursive version of Naidim's Answers.

find . -name "* *" | awk '{ print length, $0 }' | sort -nr -s | cut -d" " -f2- | while read f; do base=$(basename "$f"); newbase="${base// /_}"; mv "$(dirname "$f")/$(basename "$f")" "$(dirname "$f")/$newbase"; done

> In macOS

Just like the chosen answer.

brew install rename

# 
cd <your dir>
find . -name "* *" -type d | rename 's/ /_/g'    # do the directories first
find . -name "* *" -type f | rename 's/ /_/g'

For those struggling through this using macOS, first install all the tools:

 brew install tree findutils rename

Then when needed to rename, make an alias for GNU find (gfind) as find. Then run the code of @Michel Krelin:

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

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 _

This one does a little bit more. I use it to rename my downloaded torrents (no special characters (non-ASCII), spaces, multiple dots, etc.).

#!/usr/bin/perl

&rena(`find . -type d`);
&rena(`find . -type f`);

sub rena
{
    ($elems)=@_;
    @t=split /\n/,$elems;
    
    for $e (@t)
    {
	$_=$e;
	# remove ./ of find
	s/^\.\///;
	# non ascii transliterate
	tr [\200-\377][_];
	tr [\000-\40][_];
	# special characters we do not want in paths
	s/[ \-\,\;\?\+\'\"\!\[\]\(\)\@\#]/_/g;
	# multiple dots except for extension
	while (/\..*\./)
	{
	    s/\./_/;
	}
	# only one _ consecutive
	s/_+/_/g;
	next if ($_ eq $e ) or ("./$_" eq $e);
	print "$e -> $_\n";
	rename ($e,$_);
    }
}

Here's a reasonably sized bash script solution

#!/bin/bash
(
IFS=$'\n'
    for y in $(ls $1)
      do
         mv $1/`echo $y | sed 's/ /\\ /g'` $1/`echo "$y" | sed 's/ /_/g'`
      done
)

I found around this script, it may be interesting :)

 IFS=$'\n';for f in `find .`; do file=$(echo $f | tr [:blank:] '_'); [ -e $f ] && [ ! -e $file ] && mv "$f" $file;done;unset IFS

An easy alternative to recursive version is to increase the range of for loop step by step(n times for n sub-levels irrespective of number of sub-directories at each level). i.e from the outermost directory run these.

for f in *; do mv "$f" "${f// /_}"; done 

for f in */*; do mv "$f" "${f// /_}"; done 

for f in */*/*; do mv "$f" "${f// /_}"; done 

To check/understand what's being done, run the following before and after the above steps.

for f in *;do echo $f;done 

for f in */*;do echo $f;done 

for f in */*/*;do echo $f;done 

This only finds files inside the current directory and renames them. I have this aliased.

find ./ -name "* *" -type f -d 1 | perl -ple '$file = $_; $file =~ s/\s+/_/g; rename($_, $file);

I just make one for my own purpose. You may can use it as reference.

#!/bin/bash
cd /vzwhome/c0cheh1/dev_source/UB_14_8
for file in *
do
    echo $file
    cd "/vzwhome/c0cheh1/dev_source/UB_14_8/$file/Configuration/$file"
    echo "==> `pwd`"
    for subfile in *\ *; do [ -d "$subfile" ] && ( mv "$subfile" "$(echo $subfile | sed -e 's/ /_/g')" ); done
    ls
    cd /vzwhome/c0cheh1/dev_source/UB_14_8
done

For files in folder named /files

for i in `IFS="";find /files -name *\ *`
do
   echo $i
done > /tmp/list


while read line
do
   mv "$line" `echo $line | sed 's/ /_/g'`
done < /tmp/list

rm /tmp/list

My solution to the problem is a bash script:

#!/bin/bash
directory=$1
cd "$directory"
while [ "$(find ./ -regex '.* .*' | wc -l)" -gt 0 ];
do filename="$(find ./ -regex '.* .*' | head -n 1)"
mv "$filename" "$(echo "$filename" | sed 's|'" "'|_|g')"
done

just put the directory name, on which you want to apply the script, as an argument after executing the script.

Use below command to replace space with underscore in filename as well as directory name.

find -name "* *" -print0 | sort -rz | \
  while read -d $'\0' f; do mv -v "$f" "$(dirname "$f")/$(basename "${f// /_}")"; done