Linux chmod Command Detailed

The chmod command is used to change access rights for Linux system files or directories.

There are two ways to use this command:

One is a text-setting method that contains letters and operator expressions;

The other is a digital setting method that contains numbers.

Access to a file or directory is divided into read-only, write-only, and executable three types.

chmod Common Command Parameters

Usage:chmod [OPTION] ... Mode[,mode] ... FILE ...  Or:  chmod [OPTION] ... Octal-mode FILE  ... Or:  chmod [OPTION] ...--reference=rfile FILE ... Change the mode of each FILE to mode.  -C,--changes like verbose if only if a change is           made      --no-preserve-root does not  treat '/' specially (the default)      --preserve-root     fail to operate recursively on '/'  -F,--silent,--quiet   suppress most error messages  -V,--verbose           output a diagnostic for every file processed      --reference=rfile use   rfile ' s mode Instead of MODE values  -r,--recursive change         files and directories recursively      --help     Display this Help and exit      --version  output version information and exit

Common Command Display

421 represents the Read, write, and execute permissions for a file, respectively

chmod: Changing the value of a property
chmod 755-r/system default critical "002: Default mask for System"
CHMOD 644/system default critical "Cat/etc/profile|grep Umask can see the default umask value"

Add file All user groups executable permissions

chmod a+x log2012.log "Some scripts do not execute or do not have X permissions"

Also modify different user permissions, comma delimited

chmod ug+w,o-x Log201.log

Use "=" To set permissions

chmod u=x hhh.txt ==> chmod

Assign Read permissions to all users

chmod a=r File

Linux chmod Command Detailed