Read 644 and 755
| Mode | Symbolic bits | Meaning |
|---|---|---|
| 644 | rw-r--r-- | Owner reads and writes; group and others read. |
| 755 | rwxr-xr-x | Owner has all three permissions; group and others read and execute/search. |
| 600 | rw------- | Only the owner reads and writes. |
| 700 | rwx------ | Only the owner has these permissions. |
Use the chmod calculator to change the nine standard permission bits. A file’s leading type character in ls -l is separate from these nine bits.
A directory needs search permission
For a directory, x means search/traversal: reaching names inside it. Reading lists its entries; writing changes directory entries and normally also requires search permission. Access depends on the path’s parent directories too.
Applying 644 recursively to a directory tree removes directory search permission. A file can look readable while its parent path prevents access. Do not use 777 as a general fix for an ownership or application configuration problem.
Inspect and change a demo file
Run these commands in a fresh Bash demo directory. On GNU/Linux, stat reports the resulting numeric and symbolic permissions.
printf "demo\n" > note.txt
chmod 644 -- note.txt
ls -l -- note.txt
stat -c "%a %A" -- note.txtExpected on a regular file: 644 -rw-r--r--. Changing mode requires ownership or suitable privileges. A filesystem or mount that does not support Unix mode bits may behave differently.
Treat files and directories separately
For a simple document tree with no executable files, review these commands before running them. Substitute the intended directory; they affect every matching item below it.
find ./docs -type d -exec chmod 755 -- {} +
find ./docs -type f -exec chmod 644 -- {} +This removes executable bits from regular files, so it is unsuitable for a tree containing scripts or binaries that must remain executable. The calculator covers standard rwx bits; ACLs, ownership, sticky/setuid/setgid bits and security policies need separate inspection.