I have script which start some process but it need to login as user manoj because this script user home path /home/manoj/bin/manojprocess start

But i want to run this process automatically during the booting time but if i run it as root, my process will create some problem. So i have done following things

/etc/init.d/manojprocess
#!/bin/bash
su -c “/home/manoj/bin/manojprocess $1″ – manoj

and added the above script /etc/init.d/manojprocess into /etc/rc.local because /etc/rc.local will run after finishing init processes.

/etc/rc.local

# Start Manojprocess during booting time as Manoj user
/etc/init.d/manojprocess start

The -c Option with su command

Among the most commonly used of su’s few options is -c, which tells su to execute the command that directly follows it on the same line. Such command is executed as the new user, and then the terminal window or console from which su was run immediately returns to the account of the former user after the command has completed execution or after any program that it has launched has been closed.

If the command inclusive of its options has one or more spaces in it, then it must be enclosed in quotation marks; otherwise, su will interpret whatever comes after the first space in the command as the name of a user to whose account su is supposed to switch (the result of which will be an error message).

For example, the /root directory (i.e., the home directory of the root user) is generally not accessible to ordinary users, and thus the command ls /root will return a permission denied error message if it is issued by an ordinary user. However, the contents of this directory can be viewed (assuming, of course, that the correct password is supplied) by using su together with the ls command (which lists the contents of directories) as follows:

su -c "ls /root"

Either double or single quotation marks can be used. And a new user can be explicitly designated along with the command. For example, the following command switches to user bob’s account and produces a list of the contents of bob’s home directory (whose contents would not generally be viewable by other ordinary users):

su -c 'ls /home/manoj' - manoj


su together with its -c option can also be used to launch GUI (graphical user interface) programs. For example, it can be used to start Nautilus (a popular GUI file manager) with root access:

su -c nautilus

Nautilus can be a very handy alternative to the command line for navigating around the system. Root access makes all files and directories on the system available with Nautilus, whereas starting Nautilus as an ordinary user would make only a limited subset of files and directories available. Again, however, it should be emphasized that along with this power comes danger, and thus Nautilus should be used as root only under carefully controlled circumstances.

When a command is issued using su with its -c option, the console or terminal window session generally reverts back to the previous user as soon as the command has executed. This can be viewed as another built-in safety mechanism, because root (or any other substitute user) was apparently used just for a specific command, and thus it would presumably serve no purpose (and just be a security hole) to maintain the new ownership after the program terminated.

However, if the command that has been executed using su and its -c option has opened a program (e.g., Nautilus), that program remains open with the new owner’s (e.g., root’s) privileges until such program is explicitly closed. But the terminal window used to open the program cannot be used for other root operations while the program is running, and ownership of the session in the terminal window reverts back to the former user after the program is terminated.

One minor disadvantage of issuing commands by using the -c option with su, rather than just using su by itself (or using it together with a user name) to first change ownership of a login session, is that command line completion does not work with it. Command completion is a convenient feature of bash and some other shells that automatically completes the typing of a command name or a file name after only part of it has been typed and when the user then presses the TAB key. If su is used by itself to first switch ownership of the terminal session, command completion can then be used for subsequent commands as usual.