When multiple SCP guest commands are issued in rapid succession (by leveraging the now fixed 'cmdsep' feature), it is possible for one or more subsequent commands to be skipped/missed (not processed) while the current command is being processed.
The above .rc file was used to trigger the behavior. The guest O/S used was z/VM 6.3, but other modern operating systems (such as z/OS) behave similarly.
07:04:55 HHC01603I script "C:\Users\Fish\HercGUI\Configuration Files\scripts\cmdsep.rc.txt"
07:04:55 HHC02260I Script 1: begin processing file C:/Users/Fish/HercGUI/Configuration Files/scripts/cmdsep.rc.txt
07:04:55 HHC01603I msglvl -debug +emsgloc
07:04:55 HHC17012I MSGLEVEL = verbose nodebug emsgloc
07:04:55 HHC01603I *
07:04:55 HHC01603I *
07:04:55 HHC01603I *
07:04:55 HHC01603I * *********************************************************************
07:04:55 HHC01603I * *********************************************************************
07:04:55 HHC01603I * ********************** BEGIN TEST ***************************
07:04:55 HHC01603I * *********************************************************************
07:04:55 HHC01603I * *********************************************************************
07:04:55 HHC01603I *
07:04:55 HHC01603I cmdsep ^
07:04:55 HHC02204I CMDSEP set to ^
07:04:55 HHC01603I *
07:04:55 HHC01603I *
07:04:55 HHC01603I *
07:04:55 HHC01603I * -----------------------------------------------------------
07:04:55 HHC01603I * Each command individually with slight pause between each,
07:04:55 HHC01603I * so we can see what the correct response should look like.
07:04:55 HHC01603I * -----------------------------------------------------------
07:04:55 HHC01603I *
07:04:55 HHC01603I *
07:04:55 HHC01603I *
07:04:55 HHC00160I SCP command: q e
07:04:55 HHC02262I Script 1: processing paused for 150 milliseconds...
07:04:55 07:04:55 Q E
07:04:55 07:04:55 PRT 000E DRAINED SYSTEM CLASS A
07:04:55 07:04:55 PRT 000E FORM STANDARD MANUAL SEP NO3800 FILEFCB LIMIT NONE
07:04:55 07:04:55 PRT 000E NOFOLD IMAGE IMAG3211 CHARS A11 FCB FCB1 INDEX 1 LPP 000
07:04:55 07:04:55 PRT 000E DEST OFF DEST - NONE - DEST - NONE - DEST - NONE -
07:04:55 07:04:55 PRT 000E AFP
07:04:55 HHC02263I Script 1: processing resumed...
07:04:55 HHC01603I *
07:04:55 HHC01603I *
07:04:55 HHC01603I *
07:04:55 HHC00160I SCP command: q cons
07:04:55 HHC02262I Script 1: processing paused for 150 milliseconds...
07:04:55 07:04:55 Q CONS
07:04:55 07:04:55 CONS 0009 ON SYSC TERM START
07:04:55 07:04:55 0009 CL T NOCONT NOHOLD COPY 001 READY FORM STANDARD
07:04:55 07:04:55 0009 TO OPERATOR PRT DIST OPERATOR FLASHC 000 DEST OFF
07:04:55 07:04:55 0009 FLASH CHAR MDFY 0 FCB LPP OFF
07:04:55 07:04:55 0009 3215 NOEOF OPEN 0010 NOKEEP NOMSG NONAME
07:04:55 07:04:55 0009 SUBCHANNEL = 0005
07:04:55 HHC02263I Script 1: processing resumed...
07:04:55 HHC01603I *
07:04:55 HHC01603I *
07:04:55 HHC01603I *
07:04:55 HHC00160I SCP command: q cplevel
07:04:55 HHC02262I Script 1: processing paused for 150 milliseconds...
07:04:55 07:04:55 Q CPLEVEL
07:04:55 07:04:55 z/VM Version 6 Release 3.0, service level 1302 (64-bit)
07:04:55 07:04:55 Generated at 08/07/13 11:42:58 PST
07:04:55 07:04:55 IPL at 11/12/17 06:43:01 PST
07:04:55 HHC02263I Script 1: processing resumed...
07:04:55 HHC01603I *
07:04:55 HHC01603I *
07:04:55 HHC01603I *
07:04:55 HHC00160I SCP command: q dasd
07:04:55 HHC02262I Script 1: processing paused for 150 milliseconds...
07:04:55 07:04:55 Q DASD
07:04:55 07:04:55 DASD 0101 CP OWNED VMCOM1 12
07:04:55 07:04:55 DASD 0201 CP SYSTEM 630RL1 9
07:04:55 07:04:55 DASD 0301 CP OWNED M01RES 104
07:04:55 07:04:55 DASD 0901 CP OWNED M01S01 0
07:04:55 07:04:55 DASD 0902 CP OWNED M01P01 0
07:04:55 07:04:55 DASD 0903 CP SYSTEM M01W01 0
07:04:55 HHC02263I Script 1: processing resumed...
07:04:55 HHC01603I *
07:04:55 HHC01603I *
07:04:55 HHC01603I *
07:04:55 HHC00160I SCP command: q osa
07:04:55 HHC02262I Script 1: processing paused for 150 milliseconds...
07:04:55 07:04:55 Q OSA
07:04:55 07:04:55 OSA 0600 ATTACHED TO TCPIP 0600 DEVTYPE OSA CHPID F0 OSD
07:04:55 07:04:55 OSA 0601 ATTACHED TO TCPIP 0601 DEVTYPE OSA CHPID F0 OSD
07:04:55 07:04:55 OSA 0602 ATTACHED TO TCPIP 0602 DEVTYPE OSA CHPID F0 OSD
07:04:55 HHC02263I Script 1: processing resumed...
07:04:55 HHC01603I *
07:04:55 HHC01603I *
07:04:55 HHC01603I *
07:04:55 HHC00160I SCP command: q set
07:04:55 HHC02262I Script 1: processing paused for 150 milliseconds...
07:04:55 07:04:55 Q SET
07:04:55 07:04:55 MSG ON , WNG ON , EMSG ON , ACNT OFF, RUN ON
07:04:55 07:04:55 LINEDIT ON , TIMER OFF , ISAM OFF, ECMODE ON
07:04:55 07:04:55 ASSIST OFF , PAGEX OFF, AUTOPOLL OFF
07:04:55 07:04:55 IMSG ON , SMSG OFF , AFFINITY NONE , NOTRAN OFF
07:04:55 07:04:55 VMSAVE OFF, 370E OFF
07:04:55 07:04:55 STBYPASS OFF , STMULTI OFF 00/000
07:04:55 07:04:55 MIH OFF , VMCONIO OFF , CPCONIO OFF , SVCACCL OFF , CONCEAL OFF
07:04:55 07:04:55 MACHINE ESA, SVC76 CP, NOPDATA OFF, IOASSIST OFF
07:04:55 07:04:55 CCWTRAN ON, 370ACCOM OFF, TIMEBOMB IDLE
07:04:56 HHC02263I Script 1: processing resumed...
07:04:56 HHC01603I *
07:04:56 HHC01603I *
07:04:56 HHC01603I *
07:04:56 HHC00160I SCP command: q stor
07:04:56 HHC02262I Script 1: processing paused for 150 milliseconds...
07:04:56 07:04:56 Q STOR
07:04:56 07:04:56 STORAGE = 5G CONFIGURED = 5G INC = 1M STANDBY = 0 RESERVED = 0
07:04:56 HHC02263I Script 1: processing resumed...
07:04:56 HHC01603I *
07:04:56 HHC01603I *
07:04:56 HHC01603I *
07:04:56 HHC00160I SCP command: q sys
07:04:56 HHC02262I Script 1: processing paused for 150 milliseconds...
07:04:56 07:04:56 Q SYS
07:04:56 07:04:56
07:04:56 07:04:56 DASD 0101 ATTACHED CPVOL 0012 VMCOM1
07:04:56 07:04:56 VMSERVP 0311 R/W , VMSERVP 0310 R/W , VMSERVP 0309 R/W
07:04:56 07:04:56 VMSERVP 0308 R/W , VMSERVP 0307 R/W , VMSERVP 0306 R/W
07:04:56 07:04:56 VMSERVP 0305 R/W , VMSERVP 0304 R/W , VMSERVP 0303 R/W
07:04:56 07:04:56 VMSERVP 0301 R/W , VMSERVP 0302 R/W , VMSERVP 0191 R/W
07:04:56 07:04:56
07:04:56 07:04:56 DASD 0201 ATTACHED SYSTEM 0009 630RL1
07:04:56 07:04:56 DTCVSW1 0492 R/O , DTCVSW2 0492 R/O , TCPIP 0492 R/O
07:04:56 07:04:56 FTPSERVE 0492 R/O , DTCVSW1 0491 R/O , DTCVSW2 0491 R/O
07:04:56 07:04:56 TCPIP 0491 R/O , FTPSERVE 0491 R/O , EREP 0201 R/O
07:04:56 07:04:56
07:04:56 07:04:56 DASD 0301 ATTACHED CPVOL 0104 M01RES
07:04:56 07:04:56 OPERATOR 0191 R/W , OPERATOR 0192 R/O , FTPSERVE 0191 R/W
07:04:56 07:04:56 TCPIP 0191 R/W , VMSERVR 0307 R/W , VMSERVR 0306 R/W
07:04:56 07:04:56 VMSERVR 0305 R/W , DTCVSW1 0191 R/W , VMSERVU 0305 R/W
07:04:56 07:04:56 VMSERVR 0304 R/W , DTCVSW2 0191 R/W , VMSERVU 0304 R/W
07:04:56 07:04:56 VMSERVR 0303 R/W , DTCVSW2 0198 R/O , DTCVSW1 0198 R/O
07:04:56 07:04:56 TCPIP 0198 R/O , FTPSERVE 0198 R/O , VMSERVU 0303 R/W
07:04:56 07:04:56 VMSERVR 0302 R/W , DTCVSW2 0592 R/O , DTCVSW1 0592 R/O
07:04:56 07:04:56 TCPIP 0592 R/O , FTPSERVE 0592 R/O , VMSERVU 0302 R/W
07:04:56 07:04:56 VMSERVR 0301 R/W , DTCVSW2 0591 R/O , DTCVSW1 0591 R/O
07:04:56 07:04:56 TCPIP 0591 R/O , FTPSERVE 0591 R/O , VMSERVU 0301 R/W
07:04:56 07:04:56 VMSERVR 0191 R/W , VMSERVU 0191 R/W , VMSERVS 0305 R/W
07:04:56 07:04:56 VMSERVS 0304 R/W , VMSERVS 0303 R/W , VMSERVS 0302 R/W
07:04:56 07:04:56 VMSERVS 0301 R/W , VMSERVS 0191 R/W , OPERSYMP 0191 R/W
07:04:56 07:04:56 OPERSYMP 0192 R/O , VMSERVS 0193 R/O , VMSERVU 0193 R/O
07:04:56 07:04:56 VMSERVR 0193 R/O , VMSERVP 0193 R/O , DISKACNT 0191 R/W
07:04:56 07:04:56 EREP 0191 R/W , DISKACNT 0401 R/O , OPERSYMP 0401 R/O
07:04:56 07:04:56 VMSERVS 0401 R/O , VMSERVP 0401 R/O , DTCVSW2 0401 R/O
07:04:56 07:04:56 VMSERVU 0401 R/O , DTCVSW1 0401 R/O , VMSERVR 0401 R/O
07:04:56 07:04:56 TCPIP 0401 R/O , FTPSERVE 0401 R/O , OPERATOR 0401 R/O
07:04:56 07:04:56 DISKACNT 0402 R/O , OPERSYMP 0402 R/O , VMSERVS 0402 R/O
07:04:56 07:04:56 VMSERVP 0402 R/O , DTCVSW2 0402 R/O , VMSERVU 0402 R/O
07:04:56 07:04:56 DTCVSW1 0402 R/O , VMSERVR 0402 R/O , TCPIP 0402 R/O
07:04:56 07:04:56 FTPSERVE 0402 R/O , OPERATOR 0402 R/O , DISKACNT 019E R/O
07:04:56 07:04:56 OPERSYMP 019E R/O , VMSERVS 019E R/O , VMSERVP 019E R/O
07:04:56 07:04:56 DTCVSW2 019E R/O , VMSERVU 019E R/O , DTCVSW1 019E R/O
07:04:56 07:04:56 VMSERVR 019E R/O , TCPIP 019E R/O , FTPSERVE 019E R/O
07:04:56 07:04:56 OPERATOR 019E R/O , DISKACNT 019D R/O , OPERSYMP 019D R/O
07:04:56 07:04:56 VMSERVS 019D R/O , VMSERVP 019D R/O , DTCVSW2 019D R/O
07:04:56 07:04:56 VMSERVU 019D R/O , DTCVSW1 019D R/O , VMSERVR 019D R/O
07:04:56 07:04:56 TCPIP 019D R/O , FTPSERVE 019D R/O , OPERATOR 019D R/O
07:04:56 07:04:56 EREP 0190 R/O , DISKACNT 0190 R/O , OPERSYMP 0190 R/O
07:04:56 07:04:56 VMSERVS 0190 R/O , VMSERVP 0190 R/O , DTCVSW2 0190 R/O
07:04:56 07:04:56 VMSERVU 0190 R/O , DTCVSW1 0190 R/O , VMSERVR 0190 R/O
07:04:56 07:04:56 TCPIP 0190 R/O , FTPSERVE 0190 R/O , OPERATOR 0190 R/O
07:04:56 07:04:56 SYSTEM 0003 R/O , SYSTEM 0001 R/O
07:04:56 07:04:56
07:04:56 07:04:56 DASD 0901 ATTACHED CPVOL 0000 M01S01
07:04:56 07:04:56 DASD MDISKS NOT FOUND
07:04:56 07:04:56
07:04:56 07:04:56 DASD 0902 ATTACHED CPVOL 0000 M01P01
07:04:56 07:04:56 DASD MDISKS NOT FOUND
07:04:56 07:04:56
07:04:56 07:04:56 DASD 0903 ATTACHED SYSTEM 0000 M01W01
07:04:56 07:04:56 DASD MDISKS NOT FOUND
07:04:56 HHC02263I Script 1: processing resumed...
07:04:56 HHC01603I *
07:04:56 HHC01603I *
07:04:56 HHC01603I *
07:04:56 HHC00160I SCP command: q t
07:04:56 HHC02262I Script 1: processing paused for 150 milliseconds...
07:04:56 07:04:56 Q T
07:04:56 07:04:56 TIME IS 07:04:56 PST SUNDAY 11/12/17
07:04:56 07:04:56 CONNECT= 00:00:58 VIRTCPU= 000:00.00 TOTCPU= 000:00.06
07:04:56 HHC02263I Script 1: processing resumed...
07:04:56 HHC01603I *
07:04:56 HHC01603I *
07:04:56 HHC01603I *
07:04:56 HHC01603I * -----------------------------------------------------------
07:04:56 HHC01603I * Now do them all at once pausing slightly longer afterwards
07:04:56 HHC01603I * -----------------------------------------------------------
07:04:56 HHC01603I *
07:04:56 HHC01603I *
07:04:56 HHC01603I *
07:04:56 HHC00160I SCP command: q e
07:04:56 HHC00160I SCP command: q cons
07:04:56 HHC00160I SCP command: q cplevel
07:04:56 HHC00160I SCP command: q dasd
07:04:56 HHC00160I SCP command: q osa
07:04:56 HHC00160I SCP command: q set
07:04:56 HHC00160I SCP command: q stor
07:04:56 HHC00160I SCP command: q sys
07:04:56 HHC00160I SCP command: q t
07:04:56 HHC02262I Script 1: processing paused for 1250 milliseconds...
07:04:56 07:04:56 Q E
07:04:56 07:04:56 PRT 000E DRAINED SYSTEM CLASS A
07:04:56 07:04:56 PRT 000E FORM STANDARD MANUAL SEP NO3800 FILEFCB LIMIT NONE
07:04:56 07:04:56 PRT 000E NOFOLD IMAGE IMAG3211 CHARS A11 FCB FCB1 INDEX 1 LPP 000
07:04:56 07:04:56 PRT 000E DEST OFF DEST - NONE - DEST - NONE - DEST - NONE -
07:04:56 07:04:56 PRT 000E AFP
07:04:56 07:04:56 Q DASD
07:04:56 07:04:56 DASD 0101 CP OWNED VMCOM1 12
07:04:56 07:04:56 DASD 0201 CP SYSTEM 630RL1 9
07:04:56 07:04:56 DASD 0301 CP OWNED M01RES 104
07:04:56 07:04:56 DASD 0901 CP OWNED M01S01 0
07:04:56 07:04:56 DASD 0902 CP OWNED M01P01 0
07:04:56 07:04:56 DASD 0903 CP SYSTEM M01W01 0
07:04:56 07:04:56 Q SYS
07:04:56 07:04:56
07:04:56 07:04:56 DASD 0101 ATTACHED CPVOL 0012 VMCOM1
07:04:56 07:04:56 VMSERVP 0311 R/W , VMSERVP 0310 R/W , VMSERVP 0309 R/W
07:04:56 07:04:56 VMSERVP 0308 R/W , VMSERVP 0307 R/W , VMSERVP 0306 R/W
07:04:56 07:04:56 VMSERVP 0305 R/W , VMSERVP 0304 R/W , VMSERVP 0303 R/W
07:04:56 07:04:56 VMSERVP 0301 R/W , VMSERVP 0302 R/W , VMSERVP 0191 R/W
07:04:56 07:04:56
07:04:56 07:04:56 DASD 0201 ATTACHED SYSTEM 0009 630RL1
07:04:56 07:04:56 DTCVSW1 0492 R/O , DTCVSW2 0492 R/O , TCPIP 0492 R/O
07:04:56 07:04:56 FTPSERVE 0492 R/O , DTCVSW1 0491 R/O , DTCVSW2 0491 R/O
07:04:56 07:04:56 TCPIP 0491 R/O , FTPSERVE 0491 R/O , EREP 0201 R/O
07:04:56 07:04:56
07:04:56 07:04:56 DASD 0301 ATTACHED CPVOL 0104 M01RES
07:04:56 07:04:56 OPERATOR 0191 R/W , OPERATOR 0192 R/O , FTPSERVE 0191 R/W
07:04:56 07:04:56 TCPIP 0191 R/W , VMSERVR 0307 R/W , VMSERVR 0306 R/W
07:04:56 07:04:56 VMSERVR 0305 R/W , DTCVSW1 0191 R/W , VMSERVU 0305 R/W
07:04:56 07:04:56 VMSERVR 0304 R/W , DTCVSW2 0191 R/W , VMSERVU 0304 R/W
07:04:56 07:04:56 VMSERVR 0303 R/W , DTCVSW2 0198 R/O , DTCVSW1 0198 R/O
07:04:56 07:04:56 TCPIP 0198 R/O , FTPSERVE 0198 R/O , VMSERVU 0303 R/W
07:04:56 07:04:56 VMSERVR 0302 R/W , DTCVSW2 0592 R/O , DTCVSW1 0592 R/O
07:04:56 07:04:56 TCPIP 0592 R/O , FTPSERVE 0592 R/O , VMSERVU 0302 R/W
07:04:56 07:04:56 VMSERVR 0301 R/W , DTCVSW2 0591 R/O , DTCVSW1 0591 R/O
07:04:56 07:04:56 TCPIP 0591 R/O , FTPSERVE 0591 R/O , VMSERVU 0301 R/W
07:04:56 07:04:56 VMSERVR 0191 R/W , VMSERVU 0191 R/W , VMSERVS 0305 R/W
07:04:56 07:04:56 VMSERVS 0304 R/W , VMSERVS 0303 R/W , VMSERVS 0302 R/W
07:04:56 07:04:56 VMSERVS 0301 R/W , VMSERVS 0191 R/W , OPERSYMP 0191 R/W
07:04:56 07:04:56 OPERSYMP 0192 R/O , VMSERVS 0193 R/O , VMSERVU 0193 R/O
07:04:56 07:04:56 VMSERVR 0193 R/O , VMSERVP 0193 R/O , DISKACNT 0191 R/W
07:04:56 07:04:56 EREP 0191 R/W , DISKACNT 0401 R/O , OPERSYMP 0401 R/O
07:04:56 07:04:56 VMSERVS 0401 R/O , VMSERVP 0401 R/O , DTCVSW2 0401 R/O
07:04:56 07:04:56 VMSERVU 0401 R/O , DTCVSW1 0401 R/O , VMSERVR 0401 R/O
07:04:56 07:04:56 TCPIP 0401 R/O , FTPSERVE 0401 R/O , OPERATOR 0401 R/O
07:04:56 07:04:56 DISKACNT 0402 R/O , OPERSYMP 0402 R/O , VMSERVS 0402 R/O
07:04:56 07:04:56 VMSERVP 0402 R/O , DTCVSW2 0402 R/O , VMSERVU 0402 R/O
07:04:56 07:04:56 DTCVSW1 0402 R/O , VMSERVR 0402 R/O , TCPIP 0402 R/O
07:04:56 07:04:56 FTPSERVE 0402 R/O , OPERATOR 0402 R/O , DISKACNT 019E R/O
07:04:56 07:04:56 OPERSYMP 019E R/O , VMSERVS 019E R/O , VMSERVP 019E R/O
07:04:56 07:04:56 DTCVSW2 019E R/O , VMSERVU 019E R/O , DTCVSW1 019E R/O
07:04:56 07:04:56 VMSERVR 019E R/O , TCPIP 019E R/O , FTPSERVE 019E R/O
07:04:56 07:04:56 OPERATOR 019E R/O , DISKACNT 019D R/O , OPERSYMP 019D R/O
07:04:56 07:04:56 VMSERVS 019D R/O , VMSERVP 019D R/O , DTCVSW2 019D R/O
07:04:56 07:04:56 VMSERVU 019D R/O , DTCVSW1 019D R/O , VMSERVR 019D R/O
07:04:56 07:04:56 TCPIP 019D R/O , FTPSERVE 019D R/O , OPERATOR 019D R/O
07:04:56 07:04:56 EREP 0190 R/O , DISKACNT 0190 R/O , OPERSYMP 0190 R/O
07:04:56 07:04:56 VMSERVS 0190 R/O , VMSERVP 0190 R/O , DTCVSW2 0190 R/O
07:04:56 07:04:56 VMSERVU 0190 R/O , DTCVSW1 0190 R/O , VMSERVR 0190 R/O
07:04:56 07:04:56 TCPIP 0190 R/O , FTPSERVE 0190 R/O , OPERATOR 0190 R/O
07:04:56 07:04:56 SYSTEM 0003 R/O , SYSTEM 0001 R/O
07:04:56 07:04:56
07:04:56 07:04:56 DASD 0901 ATTACHED CPVOL 0000 M01S01
07:04:56 07:04:56 DASD MDISKS NOT FOUND
07:04:56 07:04:56
07:04:56 07:04:56 DASD 0902 ATTACHED CPVOL 0000 M01P01
07:04:56 07:04:56 DASD MDISKS NOT FOUND
07:04:56 07:04:56
07:04:56 07:04:56 DASD 0903 ATTACHED SYSTEM 0000 M01W01
07:04:56 07:04:56 DASD MDISKS NOT FOUND
07:04:56 07:04:56 Q T
07:04:56 07:04:56 TIME IS 07:04:56 PST SUNDAY 11/12/17
07:04:56 07:04:56 CONNECT= 00:00:59 VIRTCPU= 000:00.00 TOTCPU= 000:00.07
07:04:57 HHC02263I Script 1: processing resumed...
07:04:57 HHC01603I *
07:04:57 HHC01603I *
07:04:57 HHC01603I *
07:04:57 HHC01603I cmdsep off
07:04:57 HHC02204I CMDSEP set to OFF
07:04:57 HHC01603I *
07:04:57 HHC01603I * *********************************************************************
07:04:57 HHC01603I * *********************************************************************
07:04:57 HHC01603I * *********************** END TEST ****************************
07:04:57 HHC01603I * *********************************************************************
07:04:57 HHC01603I * *********************************************************************
07:04:57 HHC02264I Script 1: file C:/Users/Fish/HercGUI/Configuration Files/scripts/cmdsep.rc.txt processing ended
As you can see, several commands were skipped/missed (not processed by the guest).
I am simply creating this GitHub "Issue" for the benefit of others and so I don't forget to look into the "problem" in case it actually is a problem.