CODEWITHSUNDEEP
linuxcron
emeraldhieu
emeraldhieu

Reputation: 9439

Cron runs after other cron

I want to set a cron run after an other cron. For example: Cron A finishs at 01:00 PM, cron B will start at 01:01 PM. The problem is I don't know when cron A finishs.

I checked the crontab syntax. It doesn't provide any param for that purpose.

My actual situation is:

# This cron must run first.
? ? * * * /usr/local/bin/php -f /path/select_and_print_to_log_file.php

# two these crons runs at the same time.
0 13 * * * /usr/local/bin/php -f /path/update_user.php
0 13 * * * /usr/local/bin/php -f /path/update_image.php

# This cron runs right after two above cron completes.
? ? * * * /usr/local/bin/php -f /path/select_and_print_to_log_file.php

Upvotes: 2

Views: 1231

Answers (3)

user unknown
user unknown

Reputation: 36229

Your first job could produce a timestamp when finished.

Then you estimate - for example - that job A needs about 60 to 90 minutes. After 60 minutes, you start job B. Job b looks for the timestamp. If it is present, job B starts, else it waits for a minute and looks again.

After finishing, job B deletes the timestamp, or renames it, maybe from 'todo' to 'done'. You could insert the current date inside the file, to check, whether your estimation is still acceptable, or should be adjusted.

Upvotes: 1

Basile Starynkevitch
Basile Starynkevitch

Reputation: 1

You can use the batch command inside the first cron to have the second thing being scheduled to run.

Upvotes: 2

Conrad Shultz
Conrad Shultz

Reputation: 8808

What I do in such cases (commonly a backup scenario where I don't want to thrash the disk by having concurrent backups) is to write a script that cron calls, and in the script have the actual tasks run serially.

Something like:

#!/bin/bash

/usr/local/bin/php -f /path/update_user.php
/usr/local/bin/someOtherTaskToRunSecond

YMMV.

Upvotes: 1

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