The Problem
You're deploying a script and need the right file permissions. You type chmod 754... or was it 744? You Google it. You find a Stack Overflow thread from 2011. You get it wrong anyway.
chmod's octal notation is one of those things every Linux user has to look up constantly — and the mental model for why 755 means what it means isn't obvious unless you've memorized the bit table.
I built a free browser tool to fix that permanently.
bashsnippets.xyz/tools/chmod-permissions-builder.html
Free, no-login, browser-based. Click checkboxes for Owner, Group, and Others — and it instantly generates:
- The
chmod octal command (chmod 755 filename)
- The symbolic command (
chmod u=rwx,g=rx,o=rx filename)
- A plain-English explanation of what those permissions do
Copy and go. No fluff.
The Bit Math (Once You See It, You Can't Unsee It)
Each permission set is a 3-bit binary number:
| Permission | Binary | Octal |
|---|
--- | 000 | 0 |
--x | 001 | 1 |
-w- | 010 | 2 |
r-- | 100 | 4 |
r-x | 101 | 5 |
rw- | 110 | 6 |
rwx | 111 | 7 |
So chmod 755:
- 7 = owner →
rwx
- 5 = group →
r-x
- 5 = others →
r-x
The tool builds this visual live as you click checkboxes, so the connection between binary, octal, and the actual permissions is always visible.
Most-Used Permission Combos
chmod 755 script.sh # Executable script — owner edits, others run
chmod 644 config.conf # Config — owner edits, others read-only
chmod 600 .ssh/id_rsa # SSH private key — owner only, absolutely no one else
chmod 700 ~/scripts/ # Private directory — owner access only
Recursive Permission Application
The builder outputs a single-file command. For full directories:
# The safe way — directories and files get different permissions
find /var/www/html -type d -exec chmod 755 {} \;
find /var/www/html -type f -exec chmod 644 {} \;
⚠️ Avoid chmod -R 777 on anything that matters. It removes every security boundary between your files and other processes.
Check What's There First
ls -la filename # Human-readable
stat -c "%a" filename # Just the octal number
Use stat when you need to replicate permissions from one server to another — it gives you the exact octal to paste into the builder or chmod directly.
Try It
→ chmod Permissions Builder — bashsnippets.xyz
No login. No install. Works on mobile. If it saves you one bad deployment, it's done its job.
More free bash tools and copy-paste scripts at bashsnippets.xyz