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Richard
Asked: 2011-05-28 23:29:48 +0800 CST

Any file executed once when system starts up

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Is there any config file that is evaluated once, everytime operating system starts up. bashrc does not qualifies since it gets evaluated everytime a gnome terminal starts..

configuration

6 Answers

  1. cron can be of help here.

    Besides starting something on a minute,hour,day of week, month etc it also has some special operations:

    @reboot Run once, at startup.
@yearly Run once a year, "0 0 1 1 *".
@annually (same as @yearly)
@monthly Run once a month, "0 0 1 * *".
@weekly Run once a week, "0 0 * * 0".
@daily Run once a day, "0 0 * * *".
@midnight (same as @daily)
@hourly Run once an hour, "0 * * * *".

    Editing is done from command line with the following command:

    sudo crontab -e

    at the bottom of the file (below the # m h dom mon dow command) you can add a line that executes what you want like so @reboot /directory/to/file will execute /directory/to/file during boot.

    Just one warning: you need to make sure that there is no output from that script or that the output is redirected to a file (or /dev/null) since there is no display for cron to send the output (and it will end the operation).

    Example sudo crontab -e

    # For more information see the manual pages of crontab(5) and cron(8)
# 
PATH=/usr/sbin:/usr/bin:/sbin:/bin
# m h  dom mon dow   command
@reboot /usr/bin/testscript

    and...

    cd /usr/bin/
sudo vi testscript 
echo "works" >/tmp/testing
chmod 775 testscript

    Now for a reboot... And here is a working example:

    ls -l /tmp/testing
-rw-r--r-- 1 root root 6 2011-05-29 08:34 /tmp/testing
rinzwind@discworld:/tmp$ more /tmp/testing
works
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  2. Beside other answers, you can put your startup (superuser) commands in /etc/rc.local.

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  3. Best Answer

    There are 2 places I use when I need to add "run-once" commands:

    Once at every user login (be it Graphical/GDM or text/console login): ~/.profile

    Pros:

    • It works even if no GDM/X11/Graphical server is used. Meaning it will work with SSH and text-mode logins
    • It is NOT evaluated when a gnome terminal starts, as required. ONLY at login
    • Executed with user priveleges, its secure while allowing full access to personal scripts.
    • Run after all mounts are done, so the whole filesystem is avaliable.

    Cons:

    • If a user logs in, logs out and logs in again, it will be executed again, once per login. So its not a "true" system start up only. But it may suit your need.
    • Since this is executed even in text-mode logins, its advisable NOT to place any command that requires a GDM/X11 server (like synergy daemon)
    • Bash is only used with text-mode logins. So if using GDM, no bashisms are accepted in the script, since Ubuntu will run it with dash

    Once when GDM starts (before any user logs in): /etc/gdm/Init/Default

    Pros:

    • Executed only once, no matter how many users log in or out
    • Can be used for both text and graphical commands
    • Run after all mounts are done, so the whole filesystem is avaliable.

    Cons:

    • Run using gdm user. So personal scripts and path to them must be world-readable and executable
    • Cannot be used if no GDM server is used (duh). So it wont run in text-mode start-ups
    • Again, not run in bash, so bashisms must be avoided.

    Use the method that suits your need.

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  4. Have you looked into cron jobs? You can set one at reboot @reboot in your crontab

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  5. Just add commands to /etc/rc.local. It is executed once at the end of the boot process. Make sure you exit with error code 0. 

    (0)asus-romano:~/PDF% cat /etc/rc.local
#!/bin/sh -e
#
# rc.local
#
# This script is executed at the end of each multiuser runlevel.
# Make sure that the script will "exit 0" on success or any other
# value on error.
#
# In order to enable or disable this script just change the execution
# bits.
#
# By default this script does nothing.

exit 0

    I use this on other computer since... since... well, probably Ultrix in 1989. You have to make sure your script works invoked as root and without graphical interfaces. A way to test it is running it form a virtual console (Ctrl-Alt-F1, Ctrl-Alt-F7 to go back to your graphical environment) in a root shell (sudo -i).

    Be warned that a wrong command in that shell can completely destroy your system.

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  6. In addition to the crontab solution: You can do this (as root) noninteractively via

    echo "@reboot /path/to/runonce-script.bash" | crontab

    and put into this script a

    crontab -r

    for removing it again. Else the script will be executed after every reboot.

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