Convert folder and file names to camel case

Question

I have a list of folders and files whose names contain spaces. How can I change the names into camel case?

for oldname in *
do
  newname=`echo $oldname | sed -e 's/ /_/g'`
  if [ "$newname" = "$oldname" ]
  then
    continue
  fi
  if [ -e "$newname" ]
  then
    echo Skipping "$oldname", because "$newname" exists
  else
    mv "$oldname" "$newname"
  fi
done 

I have found this but it changes the spaces into underscores.

Answer 1

Try this Shellcheck-clean Bash code:

#! /bin/bash -p

lowers=abcdefghijklmnopqrstuvwxyz
uppers=ABCDEFGHIJKLMNOPQRSTUVWXYZ

for oldname in *; do
    [[ $oldname == *[[:space:]]* ]] || continue
    read -r -d '' -a parts <<<"$oldname"
    newname=''
    for p in "${parts[@]}"; do
        char1=${p:0:1}
        if [[ $lowers == *"$char1"* ]]; then
            tmp=${lowers%"$char1"*}
            uchar1=${uppers:${#tmp}:1}
            newname+=${uchar1}${p:1}
        else
            newname+=$p
        fi
    done
    if [[ -e $newname ]]; then
        printf "Skipping '%s', because '%s' exists\\n" "$oldname" "$newname" >&2
    else
        echo mv -v -- "$oldname" "$newname"
    fi
done

• The code is intended to work with (the now ancient) Bash 3 because my understanding is that that is still the current version of the standard Bash on macOS. The code for uppercasing the first letter of filename parts is much more complicated than it would be with later versions of Bash (which have built-in mechanisms for case conversion). See How to convert a string to lower case in Bash? for information about changing case in various ways in various versions of Bash.
• The code just prints the mv command that would be run. Remove the echo to make it actually do the mv.
• See the accepted, and excellent, answer to Why is printf better than echo? for an explanation of why I replaced echo with printf for the "Skipping" message.

For comparison, this is Bash 4+ code:

#! /bin/bash -p

for oldname in *; do
    [[ $oldname == *[[:space:]]* ]] || continue
    read -r -d '' -a parts <<<"$oldname"
    newname=''
    for p in "${parts[@]}"; do
        newname+=${p^}
    done

    if [[ -e $newname ]]; then
        printf "Skipping '%s', because '%s' exists\\n" "$oldname" "$newname" >&2
    else
        echo mv -v -- "$oldname" "$newname"
    fi
done

Answer 2

You can use the regular expression aptitude to deal with upper and lower case translations, regarding your current local collation (LC_ALL, check with the locale command).

If your filename's "words" are separated with a space and are all in lower case, you can use a simple shell script like this :

#!/bin/sh
while read -r FILENAME ; do
  NEWNAME="`echo \"${FILENAME}\" | sed 's/  *\([^ ]\)/\u\1/g'`"
  if [ ! "${NEWNAME}" ] ; then
    NEWNAME="${FILENAME}";
  fi
  if [ "${FILENAME}" = "${NEWNAME}" ]; then
    printf "No change : %s\\n" "${FILENAME}" >&2;
  else
    if [ -e "${NEWNAME}" ] ; then
      printf "Already changed : %s => %s\\n" "${FILENAME}" "${NEWNAME}" >&2;
    else
      echo "mv \"${FILENAME}\" \"${NEWNAME}\"";
    fi
  fi
done

Remove the echo on echo "mv \"${FILENAME}\" \"${NEWNAME}\""; to do the mv.

Note that it should work fine with accented letters or any unicode letter having lower and upper code.

The script takes the file list to operate from stdin, so to use it "as is", you can use something like the following examples :

• find . -type 'f' | theScript.sh

  For a whole tree of files. For folders, you'll have to operate them separately. List them and sort them in a descending order.

• ls -1 | theScript.sh

  For files in the current folder.

If your files may have all or partial upper cases at start and you look to force them entirely to camel case, you can change the line :

  NEWNAME="`echo \"${FILENAME}\" | sed 's/  *\([^ ]\)/\u\1/g'`"

With:

  NEWNAME="\`echo \"${FILENAME}\" | sed 's/\(.*\)/\l\1/;s/  *\([^ ]\)/\u\1/g'\`"

Answer 3

If you have rename installed, then all you need to do is :

rename 's/ /_/g' *