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Command Reference: try

Handles errors inside a block of code

Description

try forces a different execution behavior where a failed process at the end of a pipeline will cause the block to terminate regardless of any functions that might follow.

It’s usage is similar to try blocks in other languages (eg Java) but a closer functional example would be set -e in Bash.

To maintain concurrency within the pipeline, try will only check the last function in any given pipeline (ie series of functions joined via |, ->, or similar operators). If you need the entire pipeline checked then use trypipe.

Usage

try { code-block } -> <stdout>

<stdin> -> try { -> code-block } -> <stdout>

Examples

try {
    out: "Hello, World!" -> grep: "non-existent string"
    out: "This command will be ignored"
}

Detail

A failure is determined by:

• Any process that returns a non-zero exit number
• Any process that returns more output via STDERR than it does via STDOUT

You can see which run mode your functions are executing under via the fid-list command.

See Also

• Schedulers: Overview of the different schedulers (or ‘run modes’) in murex
• catch: Handles the exception code raised by try or trypipe
• fid-list: Lists all running functions within the current murex session
• if: Conditional statement to execute different blocks of code depending on the result of the condition
• runmode: Alter the scheduler’s behaviour at higher scoping level
• switch: Blocks of cascading conditionals
• trypipe: Checks state of each function in a pipeline and exits block on error