doc/pamtester.1.in | 4 +++-

 src/app.c          | 2 +-

 src/pamtester.c    | 7 ++++++-

 3 files changed, 10 insertions(+), 3 deletions(-)

diff --git a/doc/pamtester.1.in b/doc/pamtester.1.in

index c9b90d6..a042fab 100644

--- a/doc/pamtester.1.in

+++ b/doc/pamtester.1.in

@@ -8,7 +8,9 @@ pamtester - test pluggable authentication module (PAM) facility

 .SH DESCRIPTION

 Test pluggable authentication module (PAM) facility.

 .PP

-\fIservice\fR is the PAM service name. \fIuser\fR is the name of the user account to operate with the PAM facility. The following operations are supported.

+\fIservice\fR is the PAM service name. \fIuser\fR is the name of the user account to operate with the PAM facility. Pass "" or "NULL" to skip the user name setting.

+.PP

+The following operations are supported:

 .TP

 authenticate

 Authenticate \fIuser\fR. A conversation may subsequently take place to prompt

diff --git a/src/app.c b/src/app.c

index 9bb0aef..693bc49 100644

--- a/src/app.c

+++ b/src/app.c

@@ -210,7 +210,7 @@ int pamtester_app_run(pamtester_app_t *params)

 	}

 	if ((err = pam_start((params->service == NULL ? "": params->service),

-			(params->user == NULL ? "": params->user), &conv, &pamh))) {

+			params->user, &conv, &pamh))) {

 		err_msg = xstrdup("Initialization failure");

 		pamh = NULL;

 		goto out;

diff --git a/src/pamtester.c b/src/pamtester.c

index c1b143e..f962b31 100644

--- a/src/pamtester.c

+++ b/src/pamtester.c

@@ -170,7 +170,12 @@ int main(int argc, const char **argv)

 		goto out;

 	}

-	params.user = xstrdup(argv[op_idx++]);

+    if (0 != strcmp(argv[op_idx], "") &&

+        0 != strcmp(argv[op_idx], "NULL"))

+    {

+        params.user = xstrdup(argv[op_idx]);

+    }

+    op_idx++;

 	if (op_idx >= argc) {

 		fprintf(stderr, "%s: specify one or more operations.\n", prog_name);