OSF DCE Administration Guide--Core Components

Using the DCE Control Program Command Language

You can perform pattern-matching operations in any of several ways. Invoke ‘‘glob’’

style pattern matching with the string match command. This mimics the glob pattern

matching capabilities available in csh, returning 1 for a match and 0 for no match. More

ﬂexible regular expression pattern matching (like that found in egrep) can be performed

using regexp command. You can extend this operation to perform regular expression

substitution by using the regsub command.

The following example illustrates the use of the regsub command. The ﬁrst argument

speciﬁes the search pattern. The second argument is the string to search. The third

argument speciﬁes the replacement pattern. The last argument is a variable into which

regsub places the new string. The command returns 0 if no substitution occurs and 1 if

substitution does occur.

dcecp> regsub brown "The quick brown fox" blue color

dcecp> puts $color

The quick blue fox

2.14 Dealing with Errors and Exceptions

The dcecp interpreter includes error facilities that return error information when

something goes wrong with a dcecp script. Error information tells users what went

wrong so that they can avoid making the same mistake in the future. Many things can

cause dcecp errors. For instance, a command might not receive the correct number of

arguments, a command might have a typographic error of some kind, or the object of an

operation (such as a CDS directory) might be unavailable for some reason.

Here, we discuss three ways of dealing with errors and exceptions:

• Using global error information variables

• Catching exceptions

• Reissuing complex errors

2.14.1 UsingGlobal Error Information Variables

When dcecp encounters an error it prints a descriptive message, such as:

Error: wrong # args: should be "set varName ?newValue?"

In some cases, error messages may be insufﬁcient for determining exactly where a

problem occurred. So dcecp stores additional error information in a global variable

called errorInfo. Your script can access and print this information to help you ﬁnd the

error. Generally, it traces the commands that were executing when the error occurred.

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