scripts/mkusers: allow users with no password value set

The following allows a user definition to specify that a created user entry should not have a password value set. Original implementation allowed a user definition to provide a password value of "=" (no quotes) to generate a crypt-encoded empty string value. In some cases, it may be desired to have no value specified for a user's password. By using a value "-" for a password, no value will be set in the shadow value.

An example when this can be used is when logging into a terminal. Logging into a session with an encoded empty password will prompt a user to enter a password since it does not know the password is empty. If the password field blank, a login session will not prompt for a password.

---
Changes v1 -> v2:
- Correct error in commit message.
- More explicit example in commit message (suggested by Yann).

 docs/manual/makeusers-syntax.txt | 3 ++-
 support/scripts/mkusers          | 3 +++
 2 files changed, 5 insertions(+), 1 deletion(-)

index ffdb961..467e596 100644
@@ -31,7 +31,8 @@ Where:
   then login is disabled. If prefixed with +=+, then it is interpreted
   as clear-text, and will be crypt-encoded (using MD5). If prefixed with
   +!=+, then the password will be crypt-encoded (using MD5) and login
-  will be disabled. If set to +*+, then login is not allowed.
+  will be disabled. If set to +*+, then login is not allowed. If set to 
+  +-+, then no password value will be set.
 - +home+ is the desired home directory for the user. If set to '-', no
   home directory will be created, and the user's home will be +/+.
   Explicitly setting +home+ to +/+ is not allowed.

index 026519e..9c5c4dc 100755
@@ -318,6 +318,9 @@ add_one_user() {
         *)  fail "home must be an absolute path\n";;
     esac
     case "${passwd}" in
+        -)
+            _passwd=""
+            ;;
         !=*)
             _passwd='!'"$( encode_password "${passwd#!=}" )"
             ;;

1.9.5.msysgit.1

Dear James Knight,

Applied, thanks.

Thomas

Thomas Petazzoni, CTO, Free Electrons
Embedded Linux, Kernel and Android engineering
http://free-electrons.com