How to remove spaces and special characters from many file names

A folder of files called <code>Final Report (v2).pdf</code> and <code>Café menu #3.png</code> works on your desktop, then a script splits the names at the spaces, a link shows <code>%20</code>, or an upload rejects the <code>#</code>.

Why spaces and symbols cause trouble

• Command lines split on spaces. cp My File.txt backup/ sees two files, My and File.txt. Every script must quote names, and many do not.
• URLs escape them. A space becomes %20, # starts a fragment and cuts the link short, ? starts a query, and % itself must become %25.
• Some systems reject them. Windows refuses < > : " / \ | ? *; some upload forms, build tools and older software are stricter still.
• Accents can vary invisibly. é can be stored as one character or as e plus a combining accent (macOS often uses the second form), so two names can look identical and still differ.

A sensible naming rule

Dashes or underscores both work; pick one and keep to it. Search engines treat dashes in web addresses as word breaks, so dashes are the usual choice for files that end up online.

Clean a whole folder with a preview

1. Load the names into the batch rename tool.
2. Turn on spaces to -, remove Windows-illegal characters and lowercase. For other symbols, use find and replace with a regular expression such as [^A-Za-z0-9._-] replaced with nothing.
3. Check the table: if notes (1).txt and notes 1.txt both become notes-1.txt, it is marked as a collision and the script is held back until you fix it.
4. Copy the bash or PowerShell script and the undo script, then run it in the folder.

Quick one-liners

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

Get-ChildItem -File | Where-Object Name -match ' ' |
  Rename-Item -NewName { $_.Name -replace ' ', '-' }

Neither checks for collisions in advance: mv -n skips a file whose new name already exists, and Rename-Item stops with an error, so look at what was left behind. To turn a single title into a dashed lowercase name, the case converter has a kebab-case option, and the URL encoder shows what a name with spaces turns into inside a link.

Related

How to batch rename files safely (without uploading them) · Why a batch rename overwrites or skips files (name collisions) · Why file10 sorts before file2, and how to add leading zeros · Renaming a file when only the upper/lower case changes · Windows names you cannot use: CON, NUL, AUX, COM1 · Batch rename tool (names only, in your browser) · Compress many photos at once · Invisible characters in text

Questions

Published 8 November 2026.