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layout: default
navsection: api
title: Job tasks
navorder: 5
---

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h1. Job scripts

...how to understand and write them.

h3. Job task execution environment

A task's context is established in environment variables.

table(table table-bordered table-condensed).
|Environment variable|Description|
|@JOB_UUID@|UUID of the job|
|@JOB_PARAMETER_X@|Value of the @x@ parameter supplied when the job was created|
|@TASK_UUID@|UUID of the task|
|@TASK_QSEQUENCE@|Number of tasks added to this job before this one (in other words, 0-based queue entry order)|
|@TASK_SEQUENCE@|Task execution sequence specified when task was created — generally not unique to this task|
|@TASK_PARAMETER_X@|Value of the @x@ parameter supplied when the job task was created|
|@ARVADOS_API_TOKEN@|Authentication token to use with API calls made by the job task|