Posted under Uncategorized
One of the easiest way to edit /etc/passwd, or shadow or group file is to use “vipw” command.If you use vi to edit /etc/passwd file and if at the same time a user try to change a password while root editing file, then the user’s change will not get entered into that file.Inorder to avoid this problem and to put a lock while editing file, use vipw and vigr command which will edit the files /etc/passwd and /etc/group accordingly. You pass -s option to these command, then they will edit the shadow versions of those files i.e. /etc/shadow and /etc/gshadow, respectively.
The major purpose of locks is to prevent file corruption. Don’t use vi or other text editor to edit password file. Syntax:
* vipw -s : Edit /etc/passwd file
* vigr -s : Edit /etc/group file
Where,
* -s : Secure file editing
An example
Login as a root user:
# vipw -s
On other terminal login as normal user (for example laurel) and issue command passwd to change Laurel’s password:
$ passwd
Old UNIX password:
Enter new UNIX password:
Retype new UNIX password:
passwd: Authentication token lock busy
As you see it returned with an error “passwd: Authentication token lock busy”
This will definetly avoid /etc/shadow file corruption.
