Chmod

chmod is used to change permissions of files. If you wanna change the owner of files, please refer to chown.

usage: chmod [-param][<permission_range>+/-/=<permission_setting>] file/directory

• Change permission for "some user": chmod [u/g/o/a][+/-/=][r/w/x/-] file
  • [u/g/o/a] stands for "some user"
    • u User, the owner of file
    • g Group, the group owner of file
    • o Other, other users and groups except u and g
    • a All.
  • [+/-/=]: add permission / cancel permission / cancel all previous permissions and add the only permission
  • [r/w/x/-]: read / write / execute / none permission

• Change permission simultaneously for user(x), group(y) and others(z): chmod [xyz] file
  • x y z are integers, the sum of read(4), write(2) and execute(1).
  • eg: chmod 764 file1. User = 7 (4+2+1) r+w+x, group = 6 (4+2) r+w, other = 4 r.

• Params:
  • -c report when changes are made
  • -f do not output errors
  • -R change permissions for directory and sub files recursively.
  • -v output detailed logs