How to change file permissions with chmod - Rocketeers app [ Rocketeers ](/) [Login](https://rocketeersapp.com/login) On this page Knowledge --------- How to change file permissions with chmod ========================================= ### [\#CommandLine](https://rocketeersapp.com/knowledge/command-line) Change Linux and macOS file permissions with chmod using symbolic and numeric modes, recursive changes, and why 777 is rarely the answer. Published by [Mark van Eijk](https://rocketeersapp.com/author/mark-van-eijk) on June 23, 2026 · 2 minute read 1. [How Linux permissions work](#content-how-linux-permissions-work) 2. [Symbolic mode](#content-symbolic-mode) 3. [Numeric (octal) mode](#content-numeric-octal-mode) 4. [Recursive changes](#content-recursive-changes) 5. [A word on 777](#content-a-word-on-777) [\#](#content-how-linux-permissions-work "Permalink")How Linux permissions work ------------------------------------------------------------------------------- Every file and directory on Linux and macOS has permissions for three groups: the **user** (owner), the **group**, and **others** (everyone else). Each group can have three permissions: **read** (`r`), **write** (`w`), and **execute** (`x`). Run `ls -l` and you'll see them on the left: ``` ls -l -rw-r--r-- 1 jane staff 1240 Jun 23 10:00 notes.txt ``` The first character is the file type (`-` for a file, `d` for a directory). The next nine are three blocks of `rwx`: owner, group, others. Above, the owner can read and write, while group and others can only read. `chmod` ("change mode") is how you adjust those bits. [\#](#content-symbolic-mode "Permalink")Symbolic mode ----------------------------------------------------- Symbolic mode is the readable way to make targeted changes. You name the target (`u` user, `g` group, `o` others, `a` all), then `+`, `-`, or `=`, then the permission. ``` chmod u+x deploy.sh # give the owner execute chmod g-w report.txt # remove write from the group chmod o=r config.ini # set others to read-only exactly chmod a+r public.txt # give everyone read ``` The `+` adds, `-` removes, and `=` sets exactly (clearing anything not listed). This is my go-to when I just need to flip one bit. Making a script runnable is so common I gave it its own write-up: [make a script executable with chmod +x](/make-script-executable-chmod-x). [\#](#content-numeric-octal-mode "Permalink")Numeric (octal) mode ----------------------------------------------------------------- Numeric mode sets all three groups at once. Each digit is the sum of read (`4`), write (`2`), and execute (`1`): - `7` = `rwx` (4+2+1) - `6` = `rw-` (4+2) - `5` = `r-x` (4+1) - `4` = `r--` The three digits are owner, group, others, in that order: ``` chmod 755 deploy.sh # rwxr-xr-x — owner full, others read+execute chmod 644 notes.txt # rw-r--r-- — owner read+write, others read chmod 600 secret.key # rw------- — owner only ``` `755` is the standard for scripts and directories; `644` is standard for regular files. [\#](#content-recursive-changes "Permalink")Recursive changes ------------------------------------------------------------- To apply a mode to a directory and everything inside it, add `-R`: ``` chmod -R 755 ./public ``` Be careful here. Files and directories usually want different permissions (directories need execute to be enterable), so a blanket recursive chmod can break things. When that matters I use `find` to target each type separately: ``` find ./public -type d -exec chmod 755 {} \; find ./public -type f -exec chmod 644 {} \; ``` [\#](#content-a-word-on-777 "Permalink")A word on 777 ----------------------------------------------------- You'll see `chmod 777` suggested as a quick fix all over the internet. It grants read, write, and execute to **everyone**, which is almost never what you want. On a shared server it's a real security risk. If something isn't working, the fix is usually correct ownership (`chown`) or a sensible `644`/`755`, not throwing the doors wide open. ### Subscribe to our newsletter Do you want to receive regular updates with fresh and exclusive content to learn more about web development, hosting, security and performance? Subscribe now! 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