Step 1

Create file com.bebanjo.booklog.plist under ~/Library/LaunchAgents folder.

The following example sets standard out and error to go to a log file.

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<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE plist PUBLIC "-//Apple//DTD PLIST 1.0//EN" "http://www.apple.com/DTDs/PropertyList-1.0.dtd">
<plist version="1.0">
<dict>
    <key>Label</key>
    <string>com.bebanjo.booklog</string>
    <key>RunAtLoad</key>
    <true/>
    <key>ProcessType</key>
    <string>Background</string>
    <key>Disabled</key>
    <false/>
    <key>ProgramArguments</key>
    <array>
      <string>/Users/dst/Scripts/com.bebanjo.booklog.sh</string>
    </array>
    <key>StandardOutPath</key>
    <string>/Users/dst/Library/Logs/com.bebanjo.booklog.out</string>
    <key>StandardErrorPath</key>
    <string>/Users/dst/Library/Logs/com.bebanjo.booklog.err</string>
    <key>Debug</key>
    <true/>
</dict>
</plist>

Set valid permissions to run the user agent: chmod 700 com.bebanjo.booklog.plist

XML PROPERTY LIST KEYS

The following keys can be used to describe the configuration details of your daemon or agent. Property lists are Apple’s standard configuration file format. Please see plist(5) for more information. Please note: property list files are expected to have their name end in “.plist”. Also please note that it is the expected convention for launchd property list files to be named .plist. Thus, if your job label is “com.apple.sshd”, your plist file should be named “com.apple.sshd.plist”.

Label `<string>`

This required key uniquely identifies the job to launchd.

Disabled `<boolean>`

This optional key is used as a hint to launchctl(1) that it should not submit this job to launchd when loading a job or jobs. The value of this key does NOT reflect the current state of the job on the run-ning running ning system. If you wish to know whether a job is loaded in launchd, reading this key from a configura-tion configuration tion file yourself is not a sufficient test. You should query launchd for the presence of the job using the launchctl(1) list subcommand or use the ServiceManagement framework’s SMJobCopyDictionary() method.

Note that as of Mac OS X v10.6, this key’s value in a configuration file conveys a default value, which is changed with the [-w] option of the launchctl(1) load and unload subcommands. These subcommands no longer modify the configuration file, so the value displayed in the configuration file is not necessar-ily necessarily ily the value that launchctl(1) will apply. See launchctl(1) for more information.

Please also be mindful that you should only use this key if the provided on-demand and KeepAlive crite-ria criteria ria are insufficient to describe the conditions under which your job needs to run. The cost to have a job loaded in launchd is negligible, so there is no harm in loading a job which only runs once or very rarely.

Program `<string>`

This key maps to the first argument of execvp(3). If this key is missing, then the first element of the array of strings provided to the ProgramArguments will be used instead. This key is required in the absence of the ProgramArguments key.

ProgramArguments This key maps to the second argument of execvp(3). This key is required in the absence of the Program key. Please note: many people are confused by this key. Please read execvp(3) very carefully!

RunAtLoad `<boolean>`

This optional key is used to control whether your job is launched once at the time the job is loaded. The default is false.

StandardOutPath `<string>`

This optional key specifies what file should be used for data being sent to stdout when using stdio(3).

StandardErrorPath `<string>`

This optional key specifies what file should be used for data being sent to stderr when using stdio(3).

Debug `<boolean>`

This optional key specifies that launchd should adjust its log mask temporarily to LOG_DEBUG while dealing with this job.

ProcessType `<string>`

This optional key describes, at a high level, the intended purpose of the job. The system will apply resource limits based on what kind of job it is. If left unspecified, the system will apply light resource limits to the job, throttling its CPU usage and I/O bandwidth. The following are valid values:

Background: Background jobs are generally processes that do work that was not directly requested by the user. The resource limits applied to Background jobs are intended to prevent them from disrupting the user experience.
Standard: Standard jobs are equivalent to no ProcessType being set.
Adaptive: Adaptive jobs move between the Background and Interactive classifications based on activity over XPC connections. See xpc_transaction_begin(3) for details.
Interactive: Interactive jobs run with the same resource limitations as apps, that is to say, none. Interactive jobs are critical to maintaining a responsive user experience, and this key should only be used if an app’s ability to be responsive depends on it, and cannot be made Adaptive.

Step 2

Create file com.bebanjo.booklog.sh under ~/Scripts folder.

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#!/bin/bash --login
load_rvm
cd /Users/dst/Work/bebanjo-booklog
jekyll serve

Step 3

Run command

launchctl load -w com.bebanjo.booklog.plist

NAME

launchctl – Interfaces with launchd

DESCRIPTION

launchctl interfaces with launchd to load, unload daemons/agents and generally control launchd. launchctl supports taking subcommands on the command line, interactively or even redirected from stan-dard standard dard input. These commands can be stored in $HOME/.launchd.conf or /etc/launchd.conf to be read at the time launchd starts.

SUBCOMMANDS

load [-wF] [-S sessiontype] [-D domain] paths ...

Load the specified configuration files or directories of configuration files. Jobs that are not on-demand will be started as soon as possible. All specified jobs will be loaded before any of them are allowed to start. Note that per-user configuration files (LaunchAgents) must be owned by the user loading them. All system-wide daemons (LaunchDaemons) must be owned by root. Configuration files must not be group- or world-writable. These restrictions are in place for security reasons, as allowing writability to a launchd configuration file allows one to specify which executable will be launched.

Note that allowing non-root write access to the /System/Library/LaunchDaemons directory WILL render your system unbootable.

-w Overrides the Disabled key and sets it to false. In previous versions, this option would modify the configuration file. Now the state of the Disabled key is stored elsewhere on-disk.

Common pitfalls:

Don’t use relative paths like ~/Scripts/com.bebanjo.booklog.sh.
Don’t run launctl load -w com.bebanjo.booklog under TMUX.

Step 1

Label <string>

Disabled <boolean>

Program <string>

RunAtLoad <boolean>

StandardOutPath <string>

StandardErrorPath <string>

Debug <boolean>

ProcessType <string>