Ubuntu – Where is the cron / crontab log

Few points to make:

• Why are you using timestrings in /etc/cron.weekly/ scripts at all? You're only supposed to put executable scripts in there. You don't need to crontab them or anything else. That will just duplicate their work. Look at /etc/cron.daily/apt for an example of what I'm talking about. It's just a plain script.

• Per geirha's comment, the file can't have an extension. Odd, I know, so rename it:

  sudo mv /etc/cron.weekly/mysqlbackup{.sh,}
  

• You need to run sudo chmod +x /etc/cron.weekly/mysqlbackup to make it executable. You can then test it by running it, using that path.

• If you leave it in /etc/cron.weekly/, the script is going to run as root. None of your ~/ links are going to work. Use full paths. I'd suggest that after you do the mkdir you cd into it and that will reduce the huge paths in subsequent commands. If you need the generated files to be owned by your user, make your script chown them to your user when it's done backing up.

  I don't see any reason for any of this to be root driven. You could plonk the script in your home directory and just use the standard crontab -e to add your rule and have it run. It still needs to be executable and I'd still recommend you use full paths, but it keeps the permissions slightly easier.

The syntax for the crontab entry looks correct. Indeed, if you edit your crontab using "crontab -e" (as you should), you'll get an error if you specify a syntactically invalid crontab entry anyway.

1. Firstly, does /path_to_my_php_script/info.php run correctly from the command-line?

2. If so, does it also run correctly like this?:

   /bin/sh -c "(export PATH=/usr/bin:/bin; /path_to_my_php_script/info.php </dev/null)"
   

3. If that works, does it work like this?

   /bin/sh -c "(export PATH=/usr/bin:/bin; /path_to_my_php_script/info.php </dev/null >/dev/null 2>&1)"
   

Step (3) is similar to how cron will run your program (as documented in "man 5 cron".

The most likely problem you're having is that the PATH cron is using to run your program is too restrictive. Therefore, you may wish to add something like the following to the top of your crontab entry (you'll need to add in whatever directories your script will need):

PATH=~/bin:/usr/bin/:/bin

Also note that cron will by default use /bin/sh, not bash. If you need bash, also add this to the start of your crontab file:

SHELL=/bin/bash

Note that both those changes will affect all the crontab entries. If you just want to modify these values for your info.php program, you could do something like this:

*/2 * * * * /bin/bash -c ". ~/.bashrc; /path_to_my_php_script/info.php"

It's also worth mentioning that on a system configured for "mail" (in other words a system which has an MTA configured [sendmail/postfix/etc]), all output from crontab programs is sent to you via email automatically. A default Ubuntu desktop system won't have local mail configured, but if you're working on a server you can just type "mail" in a terminal to see all those cron mails. This also applies to the "at" command.