Install of TrueSight Infrastructure Management (TSIM) fails with "CSH shell is not installed on the system." even though csh shell is installed.

The install log shows permission denied when executing the script that checks if csh shell is present even though /tmp and the file /tmp/cShellValidationScript.sh have execute permissions:

 ********************* Check starts: validateCShellInstallation **********************]}
(Nov 13 2020 07:30:11.470 AM +0000),INFO,com.bmc.install.product.bppm.server.preinstall.BPPMServerServerPreInstall,
  LOG EVENT {Description=[ <SERVER_INSTALL> cshellValidationScript: /tmp/cShellValidationScript.sh],Detail=[ Script file found]}
(Nov 13 2020 07:30:11.470 AM +0000),INFO,com.bmc.install.product.bppm.util.BPPMCommandExecuter,
  LOG EVENT {Description=[ <SERVER_INSTALL> Executing Command:  /tmp/cShellValidationScript.sh],Detail=[]}
(Nov 13 2020 07:30:11.471 AM +0000),WARNING,com.bmc.install.product.bppm.util.BPPMCommandExecuter,
  LOG EVENT {Description=[ <SERVER_INSTALL> Unable to execute command successfully. Command: [/tmp/cShellValidationScript.sh] with return code: -1, Output: Exception running command: Cannot run program "/tmp/cShellValidationScript.sh": error=13, Permission denied
, OutputLines: [Exception running command: Cannot run program "/tmp/cShellValidationScript.sh": error=13, Permission denied]],Detail=[]}
(Nov 13 2020 07:30:11.471 AM +0000),WARNING,com.bmc.install.task.InstallationStateHelper,
  LOG EVENT {Description=[BMC TrueSight Infrastructure Management Server warned],Detail=[SERVER]}
(Nov 13 2020 07:30:11.471 AM +0000),INFO,com.bmc.install.product.bppm.server.preinstall.BPPMServerServerPreInstall,
  LOG EVENT {Description=[ <SERVER_INSTALL> command output = Exception running command: Cannot run program "/tmp/cShellValidationScript.sh": error=13, Permission denied
]}
(Nov 13 2020 07:30:11.471 AM +0000),INFO,com.bmc.install.product.bppm.server.preinstall.BPPMServerServerPreInstall,
  LOG EVENT {Description=[ <SERVER_INSTALL> Failed to execute c-shell installation validation command, return code: -1],Detail=[]}