Remove unwanted exit

.gitignore

 build/*
 bin/*
 test/docker/*/agent/*
+test/log.txt

src/linux/get_user_count.cpp

@@ -294,7 +294,7 @@ static struct user_log * last_modified () {
         if (x == ENOENT)
             fprintf(stderr, "Perhaps this file was removed by the "
                 "operator to prevent logging info.\n");
-        exit(1);
+        return NULL;
     }
 
     /*
@@ -425,7 +425,8 @@ static struct user_log * last_modified () {
                     break;
                 if ((p = (struct utmplist *)malloc(sizeof(struct utmplist))) == NULL) {
                     fprintf(stderr, "ERROR: out of memory\n");
-                    exit(1);
+                    return NULL;
+                    
                 }
                 memcpy(&p->ut, &ut, sizeof(struct utmp));
                 p->next  = utmplist;
@@ -542,7 +543,7 @@ static struct user_log * last_modified () {
                     break;
                 if ((p = (struct utmplist *)malloc(sizeof(struct utmplist))) == NULL) {
                     fprintf(stderr, "ERROR: out of memory\n");
-                    exit(1);
+                    return NULL;
                 }
                 memcpy(&p->ut, &ut, sizeof(struct utmp));
                 p->next  = utmplist;
@@ -575,7 +576,7 @@ int get_user_count () {
 
     strftime (yesterday,7,"%y%m%d",timeinfo);
     yesterday[6] = '\0';
-
+    
     for(i = u; i; i = u){
         if(!strcmp(i->logout,"999999")){
             if(strcmp(i->login,yesterday) <= 0){