diff --git a/src/frontend/com_plot.c b/src/frontend/com_plot.c
index 6758dbd04..b151849bb 100644
--- a/src/frontend/com_plot.c
+++ b/src/frontend/com_plot.c
@@ -7,11 +7,17 @@
 
 #include "com_plot.h"
 
+extern bool ft_batchmode;
 
 /* plot name ... [xl[imit]] xlo xhi] [yl[imit ylo yhi] [vs xname] */
 void
 com_plot(wordlist *wl)
 {
+    if (ft_batchmode) {
+        fprintf(stderr, "\nWarning: command 'plot' is not available during batch simulation, ignored!\n");
+        fprintf(stderr, "    You may use Gnuplot instead.\n\n");
+        return;
+    }
     plotit(wl, NULL, NULL);
 }
 
diff --git a/src/frontend/display.c b/src/frontend/display.c
index a85a30726..a286289f5 100644
--- a/src/frontend/display.c
+++ b/src/frontend/display.c
@@ -129,7 +129,7 @@ DISPDEVICE device[] = {
       (disp_fn_Track_t *) NODEV, (disp_fn_MakeMenu_t *) NODEV, (disp_fn_MakeDialog_t *) NODEV, (disp_fn_Input_t *) NODEV,
       gen_DatatoScreen, },
 
-    { "PrinterOnly", 0, 0, 24, 80, 0, 0,
+    { "BatchMode/PrinterOnly", 0, 0, 24, 80, 0, 0,
       (disp_fn_Init_t *) NODEV, (disp_fn_NewViewport_t *)  NODEV,
       (disp_fn_Close_t *) NOP, (disp_fn_Clear_t *) NODEV,
       (disp_fn_DrawLine_t *) NODEV, (disp_fn_Arc_t *) NODEV, (disp_fn_Text_t *) NODEV,
diff --git a/src/frontend/inp.c b/src/frontend/inp.c
index ed9415156..0b0c21f2c 100644
--- a/src/frontend/inp.c
+++ b/src/frontend/inp.c
@@ -980,6 +980,11 @@ inp_spsource(FILE *fp, bool comfile, char *filename, bool intfile)
         }
 
         for (dd = deck; dd; dd = dd->nextcard) {
+            /* first line is title line, skip it */
+            if (deck == dd) {
+                prev_card = dd;
+                continue;
+            }
             /* all parameter lines should be sequentially ordered and placed at
                beginning of deck */
             if (ciprefix(".para", dd->line)) {
diff --git a/src/frontend/numparam/xpressn.c b/src/frontend/numparam/xpressn.c
index 7df535340..e7ce0e1ee 100644
--- a/src/frontend/numparam/xpressn.c
+++ b/src/frontend/numparam/xpressn.c
@@ -1395,6 +1395,8 @@ nupa_assignment(dico_t *dico, const char *s, char mode)
    bug: we cannot rely on the transformed line, must re-parse everything!
 */
 {
+    if (!s || !*s)
+        return 1;
     /* s has the format: ident = expression; ident= expression ...  */
     const char * const s_end = s + strlen(s);
     const char *p = s;
diff --git a/src/main.c b/src/main.c
index bba99a714..7957cc7f2 100644
--- a/src/main.c
+++ b/src/main.c
@@ -19,6 +19,7 @@
 #ifdef HAVE_GNUREADLINE
 # include <readline/readline.h>
 # include <readline/history.h>
+# include "../misc/tilde.h"
 #endif
 
 /* editline development has added the following typdef to readline.h in 06/2018.
@@ -614,11 +615,15 @@ static void
 app_rl_init(void)
 {
 #if defined(HAVE_GNUREADLINE) || defined(HAVE_BSDEDITLINE)
+    char *home;
+
     /* ---  set up readline params --- */
-    strcpy(history_file, getenv("HOME"));
-    strcat(history_file, "/.");
-    strcat(history_file, application_name);
-    strcat(history_file, "_history");
+
+    if (get_local_home(0, &home) < 0)
+        return;
+    snprintf(history_file, sizeof history_file, "%s/.%s_history",
+             home, application_name);
+    tfree(home);
 
     using_history();
     read_history(history_file);
@@ -1403,6 +1408,8 @@ int main(int argc, char **argv)
 
     if (ft_batchmode) {
 
+        int error3 = 1;
+
         /* If we get back here in batch mode then something is wrong,
          * so exit.  */
 
@@ -1425,6 +1432,9 @@ int main(int argc, char **argv)
 
         cp_interactive = FALSE;
 
+        /* Check if a simulation has run from a .control section */
+        cp_getvar("sim_status", CP_NUM, &error3, 0);
+
         if (rflag) {
             /* If -r is specified, then dot cards (.width, .plot, .print, .op, .meas, .tf)
                are ignored, except .save, which has been handled by ft_dotsaves()
@@ -1443,6 +1453,10 @@ int main(int argc, char **argv)
             if (ft_cktcoms(FALSE) || error2)
                 sp_shutdown(EXIT_BAD);
         }
+        else if (error3 == 0) {
+            fprintf(stdout, "Note: Simulation executed from .control section \n");
+            sp_shutdown(EXIT_NORMAL);
+        }
         else {
             fprintf(stderr,
                     "Note: No \".plot\", \".print\", or \".fourier\" lines; "
diff --git a/src/sharedspice.c b/src/sharedspice.c
index af9dccd02..5e4145a55 100644
--- a/src/sharedspice.c
+++ b/src/sharedspice.c
@@ -2033,7 +2033,8 @@ ATTRIBUTE_NORETURN void shared_exit(int status)
         fl_exited = TRUE;
         bgtr(fl_exited, ng_ident, userptr);
         // set a flag that ngspice wants to be detached
-        ngexit(status, FALSE, coquit, ng_ident, userptr);
+        if(ngexit)
+            ngexit(status, FALSE, coquit, ng_ident, userptr);
         // finish and exit the worker thread
 #ifdef HAVE_LIBPTHREAD
         pthread_exit(NULL);
@@ -2042,7 +2043,8 @@ ATTRIBUTE_NORETURN void shared_exit(int status)
 #endif
     }
     // set a flag in caller to detach ngspice.dll
-    ngexit(status, immediate, coquit, ng_ident, userptr);
+    if(ngexit)
+        ngexit(status, immediate, coquit, ng_ident, userptr);
 
     // jump back to finish the calling function
     if (!intermj)
diff --git a/src/spicelib/devices/isrc/isrctemp.c b/src/spicelib/devices/isrc/isrctemp.c
index 207ed69a8..92f3e64a0 100644
--- a/src/spicelib/devices/isrc/isrctemp.c
+++ b/src/spicelib/devices/isrc/isrctemp.c
@@ -42,7 +42,9 @@ ISRCtemp(GENmodel *inModel, CKTcircuit *ckt)
                     here->ISRCname);
             }
             else if (here->ISRCdcGiven && here->ISRCfuncTGiven
-                && here->ISRCfunctionType != TRNOISE && here->ISRCfunctionType != TRRANDOM) {
+                    && here->ISRCfunctionType != TRNOISE
+                    && here->ISRCfunctionType != TRRANDOM
+                    && here->ISRCfunctionType != EXTERNAL) {
                 /* DC value and transient time 0 values given */
                 double time0value;
                 /* determine transient time 0 value */
diff --git a/src/spicelib/devices/vsrc/vsrctemp.c b/src/spicelib/devices/vsrc/vsrctemp.c
index 413a7392e..413e356e9 100644
--- a/src/spicelib/devices/vsrc/vsrctemp.c
+++ b/src/spicelib/devices/vsrc/vsrctemp.c
@@ -48,7 +48,9 @@ VSRCtemp(GENmodel *inModel, CKTcircuit *ckt)
                     here->VSRCname);
             }
             else if (here->VSRCdcGiven && here->VSRCfuncTGiven
-                     && here->VSRCfunctionType != TRNOISE && here->VSRCfunctionType != TRRANDOM) {
+                     && here->VSRCfunctionType != TRNOISE
+                     && here->VSRCfunctionType != TRRANDOM
+                     && here->VSRCfunctionType != EXTERNAL) {
                 /* DC value and transient time 0 values given */
                 double time0value;
                 /* determine transient time 0 value */
diff --git a/src/spicelib/parser/inp2dot.c b/src/spicelib/parser/inp2dot.c
index f1ba03623..bf035e52d 100644
--- a/src/spicelib/parser/inp2dot.c
+++ b/src/spicelib/parser/inp2dot.c
@@ -182,6 +182,7 @@ dot_ac(char *line, CKTcircuit *ckt, INPtables *tab, struct card *current,
     IFvalue *parm;		/* a pointer to a value struct for function returns */
     int which;			/* which analysis we are performing */
     char *steptype;		/* ac analysis, type of stepping function */
+    bool pdef = FALSE;  /* issue a warning if default parameters are used */
 
     NG_IGNORE(gnode);
 
@@ -193,15 +194,33 @@ dot_ac(char *line, CKTcircuit *ckt, INPtables *tab, struct card *current,
     }
     IFC(newAnalysis, (ckt, which, "AC Analysis", &foo, task));
     INPgetTok(&line, &steptype, 1);	/* get DEC, OCT, or LIN */
+    if (!*steptype || (!ciprefix("dec", steptype) && !ciprefix("oct", steptype) && !ciprefix("lin", steptype))) {
+        current->error = "Missing DEC, OCT, or LIN\n";
+        return (0);
+    }
     ptemp.iValue = 1;
     GCA(INPapName, (ckt, which, foo, steptype, &ptemp));
     tfree(steptype);
+
     parm = INPgetValue(ckt, &line, IF_INTEGER, tab); /* number of points */
+    if (parm->iValue == 0)
+        pdef = TRUE;
     GCA(INPapName, (ckt, which, foo, "numsteps", parm));
+
+    if(!isdigit(*line))
+        pdef = TRUE;
     parm = INPgetValue(ckt, &line, IF_REAL, tab);	/* fstart */
     GCA(INPapName, (ckt, which, foo, "start", parm));
+
     parm = INPgetValue(ckt, &line, IF_REAL, tab);	/* fstop */
+    if (parm->rValue == 0)
+        pdef = TRUE;
     GCA(INPapName, (ckt, which, foo, "stop", parm));
+
+    if (pdef) {
+        fprintf(stderr, "Warning, ngspice assumes default parameter(s) for ac simulation\n");
+        fprintf(stderr, "    Check your ac or .ac line\n\n");
+    }
     return (0);
 }
 
diff --git a/src/spicelib/parser/inpgtok.c b/src/spicelib/parser/inpgtok.c
index 58ece2fc1..be17a1a3f 100644
--- a/src/spicelib/parser/inpgtok.c
+++ b/src/spicelib/parser/inpgtok.c
@@ -31,6 +31,11 @@ INPgetTok(char **line, char **token, int gobble)
     char *point;
     int signstate;
 
+    if (!*line) {
+        *token = NULL;
+        return (E_PARMVAL);
+    }
+
     /* scan along throwing away garbage characters until end of line
        or a separation char is found */
     for (point = *line; *point != '\0'; point++) {