onCommandCompletion

Trigger an event upon a command's completion

Description

onCommandCompletion events are triggered after a command has finished executing in the interactive terminal.

Background processes or commands ran from inside aliases, functions, nested blocks or from shell scripts cannot trigger this event. This is to protect against accidental race conditions, infinite loops and breaking expected behaviour / the portability of Murex scripts. On those processes directly ran from the prompt can trigger this event.

Usage

event onCommandCompletion name=command { code block }

!event onCommandCompletion name

Valid Interrupts

• <command> Name of command that triggers this event

Payload

The following payload is passed to the function via stdin:

{
    "Name": "",
    "Interrupt": {
        "Command": "",
        "Parameters": [],
        "Stdout": "",
        "Stderr": "",
        "ExitNum": 0
    }
}

Name

This is the name you specified when defining the event.

Interrupt/Command

Name of command executed prior to this event being triggered.

Interrupt/Parameters

The command line parameters of the aforementioned command.

This will be an array of strings, like @ARGV.

Interrupt/Stdout

This is the name of the Murex named pipe which contains a copy of the stdout from the command which executed prior to this event.

You can read this with read-named-pipe. eg

» <stdin> -> set: event
» read-named-pipe: $event.Interrupt.Stdout -> ...

Interrupt/Stderr

This is the name of the Murex named pipe which contains a copy of the stderr from the command which executed prior to this event.

You can read this with read-named-pipe. eg

» <stdin> -> set: event
» read-named-pipe: $event.Interrupt.Stderr -> ...

Interrupt/ExitNum

This is the exit number returned from the executed command.

Event Return

This event doesn't have any $EVENT_RETURN parameters.

Examples

Read stderr

In this example we check the output from pacman, which is ArchLinux's package management tool, to see if you have accidentally ran it as a non-root user. If the stderr contains a message saying you are no root, then this event function will re-run pacman with sudo.

event onCommandCompletion sudo-pacman=pacman {
    <stdin> -> set event
    read-named-pipe $event.Interrupt.Stderr \
    -> regexp 'm/error: you cannot perform this operation unless you are root/' \
    -> if {
          sudo pacman @event.Interrupt.Parameters
       }
}

Detail

Standard out and error

Stdout and stderr are both written to the terminal's stderr.

See Also

• Alias Pointer (alias): Create an alias for a command
• If Conditional (if): Conditional statement to execute different blocks of code depending on the result of the condition
• Murex Event Subsystem (event): Event driven programming for shell scripts
• Named Pipes: A detailed breakdown of named pipes in Murex
• Public Function (function): Define a function block
• Read From Stdin (<stdin>): Read the stdin belonging to the parent code block
• Regex Operations (regexp): Regexp tools for arrays / lists of strings
• Shell Configuration And Settings (config): Query or define Murex runtime settings
• ARGV (json): Array of the command name and parameters within a given scope
• onPrompt: Events triggered by changes in state of the interactive shell
• read-named-pipe: Reads from a Murex named pipe

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This document was generated from builtins/events/onCommandCompletion/oncommandcompletion_doc.yaml.