memleak: Print error message if fewer than 2 arguments are supplied.

memleak/memory-consumption-over-time.gp

@@ -3,21 +3,27 @@
 # smem -P '^myprogram' -t | tail -n1 \
 #   | awk '{print "USS:", $4; print "PSS:",$5; print "RSS:",$6; print "SWP:",$3;}' \
 #   | sed "s/:/ $(date --iso-8601=minutes)/" >> mem-myprogram.data
-
+#
+# Arguments: <program name> <time of first data point> [width] [height]
 # Example usage: ./memory-consumption-over-time.gp myprogram 2021-12-05T08:42
 
-if (ARGC > 0) {
+if (ARGC < 2) {
+    printerr "You probably want to supply the program name ", \
+             "and the time of first data point. ", \
+             "See the header of this script for more information."
+}
+
+myprog='unknown'
+if (ARGC >= 1) {
     myprog = ARG1
-} else {
-    myprog='unknown'
 }
 infile=sprintf('mem-%s.data', myprog)
 
 mytimefmt = "%Y-%m-%dT%H:%M"
-if (ARGC > 1) {
+mystarttime = strptime(mytimefmt, "1970-01-01T00:00")
+if (ARGC >= 2) {
     mystarttime = strptime(mytimefmt, ARG2)
-} else {
-    mystarttime = strptime(mytimefmt, "1970-01-01T00:00")
+}
 }
 
 set title sprintf('%s memory consumption over time', myprog)