# Linux How to remove all permissions on a file or directory and protect it

## Remove all permissions on directory perm_tes of Owner(u), Group(g), others(o) and all(a)
`chmod 000 perm_test`
or
`chmod 0 perm_test`
or
`chmod a=--- perm_test`
or
`chmod a=- perm_test`


## Open Read permission of Owner on directory perm_tes
`chmod 400 perm_test`
or
`chmod u=r perm_test`

## Open Read Write permission of Owner on directory perm_tes
`chmod 600 perm_test`
or
`chmod u=rw perm_test`

## Open Read Write Exec permission of Owner on directory perm_tes
`chmod 700 perm_test`
or
`chmod u=rwx perm_test`

## Open Read Write Exec permission of Owner on directory perm_tes and its all sub directories and files
`chmod 700 perm_test`
or
`chmod u=rwx perm_test`

-------------------

## Remove all permissions on file perm_test/address.txt of Owner
`chmod  u=- perm_test/address.txt`

## Open Read permission of Owner on file address.txt
`chmod  u=r perm_test/address.txt`

## Open Read Write permission of Owner on file address.txt
`chmod  u=rw perm_test/address.txt`

-----------------

## R emove all permissions on file perm_test/address.txt of group
`chmod  g=- perm_test/address.txt`

## Open Read permission of group on file address.txt
`chmod  g=r perm_test/address.txt`

## Open Read Write permission of group on file address.txt
`chmod  g=rw perm_test/address.txt`

-----------------

## Remove all permissions on file perm_test/address.txt of others
`chmod  o=- perm_test/address.txt`

## Open Read permission of others on file address.txt
`chmod  o=r perm_test/address.txt`

## Open Read Write permission of others on file address.txt
`chmod  o=rw perm_test/address.txt`

-----------------

## Remove all permissions on file perm_test/address.txt of owner and group
`chmod  ug=- perm_test/address.txt`

## Remove all permissions on file perm_test/address.txt of owner,group and others
`chmod  ugo=- perm_test/address.txt`

## Add Write permissions on file perm_test/address.txt for owner
`chmod  u+w perm_test/address.txt`

## Add Write permissions on file perm_test/address.txt for owner and group
`chmod  ug+w perm_test/address.txt`

## Add Read Write permissions on file perm_test/address.txt for owner and group
`chmod  ug+rw perm_test/address.txt`

## Remove Write permissions on file perm_test/address.txt for owner
`chmod  u+w perm_test/address.txt`

## Remove write permissions on file perm_test/address.txt for owner and group
`chmod  ug-w perm_test/address.txt`

## Remove Read Write permissions on file perm_test/address.txt for owner and group
`chmod  ug-rw perm_test/address.txt`

-----------------

## Add Read Write permissions on file perm_test/address.txt for all (owner,group and others)
`chmod  a+rw perm_test/address.txt`

## Remove Read Write permissions on file perm_test/address.txt for all (owner,group and others)
`chmod  a-rw perm_test/address.txt`