chmod a+r junk

This command will remove the permission to execute the file junk from others

chmod o-x junk

You can set the default file permissions for the new files that you create using this command.

umask (see man umask).

chown new_ownername filename and

chgrp new_groupname filename

Change the file owner and group. You should use these two commands after you copy a file for use by somebody else.

su

Assume the superuser (root) identity (you will be prompted for the password). Type exit to return you to your previous login. Don’t habitually work on your machine as root. The root account is for administration and the su command is to ease your access to the administration account when you require it.

rpm -ivh filename.rpm

Redhat Package Manager, install, verbose, hashes displayed to show progress, as root.) Install the contents of a rpm package and print info on what happened.

rpm -qpi filename.rpm

Redhat Package Manager, query, package, list.)

Read the info on the contents of a un-installed package filename.rpm.

rpm -qpl filename.rpm

(Redhat Package Manager, query, package,information.)

List the files contained in a yet un-installed package filename.rpm.

rpm -qf filename

(Redhat Package Manager, query, file.)

Find out the name of the *.rpm package to which the file filename (on your hard drive)

belongs.

rpm -e packagename

(Redhat Package Manager, erase un-install.)

Un-install a package pagckagename. Package name is the same as the beginning of the *.rpm package

(without the dash and version number).

lsmod

List currently loaded kernel modules.

modprobe -l |more

List all the modules available for your kernel.

insmod parport

insmod = ppa (as root) Insert modules into the kernel (a module is roughly an equivalent of a DOS device driver). This example shows how to insert the modules for support of the external parallel port zip drive (it appears to be a problem to get the external zip drive to work in any other way under RH6.0 ).

rmmod module_name

(as root, not essential). Remove the module module_name from the kernel.

setserial /dev/cua0 port 0x03f8 irq = 4

(as root) Set a serial port to a non-standard setting. The example here shows the standard setting for the first serial port (cua0 or ttyS0).