Automatically run programs in Red Hat Linux

1. automatically run the program at startup

After Linux is loaded, it initializes the hardware and device drivers, and then runs the first process init. Init starts other processes based on the configuration file. Normally, the modification is placed in/etc/rc or/etc/rc. d or/etc/rc ?. The script file in the d directory can enable init to automatically start other programs. For example, to edit the/etc/rc. d/rc. local file, add "xinit" or "startx" at the end of the file. You can directly enter X-Window after the file is started.
　　
2. automatically run the program upon Logon

When a user logs on, bash automatically runs the global logon script:/ect/profile created by the system administrator. Bash then searches for one of the three special files in sequence in the user's starting Directory:/. bash_profile,/. bash_login, And/. profile, but only executes the first one found.
Therefore, you only need to add commands to the above files as needed to automatically run certain programs (similar to Autoexec. bat in DOS) during user logon ).
　　
3. automatically run the program upon logon.

When you log out, bash automatically runs the personal logout script/. bash_logout. For example /. in bash_logout, add the command tar-cvzf c. source. tgz *. c, the "tar" command is automatically executed every time you log out to back up *. c file.

4. Periodically run the program automatically

Linux has a daemon called crond. Its main function is to periodically check the content of a group of command files in the/var/spool/cron directory, and execute the commands in these files at the specified time. You can use the crontab command to create, modify, and delete these command files.

For example, create a crondFile with the content "00 9 23 Jan * HappyBirthday". After running the "crontab cronFile" command, every time the system automatically executes the "HappyBirthday" program at AM on March 23, lunar January ("*" indicates that no matter the day of the day is the day of the week ).
　　
5. automatically run the program once at a scheduled time

Scheduled command execution at is similar to crond (but it is only executed once): The command is executed at a given time, but is not automatically repeated. The at command is generally in the format of at [-f file] time. All commands in the file are executed at the specified time. You can also enter the command directly from the keyboard:

$ At 12: 00
At> mailto Roger-s "Have a lunch" <plan.txt
At> Ctr-D
Job 1
At, an email entitled "Have a lunchtasks, containing the plan.txt file content was automatically sent to Roger .?
At, February 9, an email entitled "Have a lunch.pdf containing the plan.txt file was automatically sent to Roger. Er. Ger. Er.