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Determining Which Shell is Used

A shell is a program that provides an environment for users to interact with the system. Shell programs are files that contain a series of user commands that are grouped, using logic provided by the shell, to accomplish a task.

Shells can be defined by you, the script’s programmer, your agent administrator, and your UNIX administrator. When you define a job that runs on UNIX, you may want to know which shell is used to run the script because different shells have different facilities and characteristics. Some functions are specific to certain shells and may be incompatible with other shells.

The shell used is determined by the following settings in the following order:

1. The SHELL statement (if specified in the job definition)
2. The first line of the script (if the SHELL statement is not specified)
3. The oscomponent.defaultshell parameter in the agent's agentparm.txt file (if not specified in the SHELL statement or in the script)
4. The user default shell defined in the user profile (if not specified in one of the previous three locations)

Notes:

• If the shell is defined in the first line of the script, you do not need to include the SHELL statement in the job definition.
• If the oscomponent.checkvalidshell parameter in the agent's agentparm.txt file is set to true (the default), all shells that are used must be specified using the oscomponent.validshell parameter. The path defined in the first line of the script or in the job definition must match the corresponding path in the oscomponent.validshell parameter. If the shell you want to use is not defined on the agent, the job fails. For more information about specifying valid shells, see the oscomponent.checkvalidshell and oscomponent.validshell parameters in the CA Workload Automation Agent for UNIX, Linux, or Windows Implementation Guide.

Example: Specify the Shell in the SHELL Statement

In this example, the C shell is specified in the SHELL statement.

AGENT UNIX_LA
SCRIPTNAME /mfg/test1.csh
SHELL /bin/csh

Example: Specify the Shell in the First Line of the Script

The first line of the following test1.csh script identifies the C shell:

#!/bin/csh -f
if ( $LOGNAME != guest) then

echo "User is not guest"

endif
echo $LOGNAME logon
exit 0

The following job definition does not contain the SHELL statement:

AGENT UNIX_LA
SCRIPTNAME /mfg/test1.csh
USER guest

In this example, agent UNIX_LA runs the test1.csh script using the C shell.