Ubuntu

Scheduling in Linux…

Linux comes equipped with scheduling tools. Tools that will let you get a full night’s rest and still have that backup program automatically run at 3am on the dot, and even send us an email letting us know about any appointments.

1. Using the at utility

The at command is used for jobs that need to be run only once. at is an interactive program and it takes in an argument, which is the time and date that you want the job to be run. All outputs of at are sent by email. So let’s say it’s 1pm, and we have a meeting at 3pm. In order to be reminded of this meeting at 2:30pm, we can type:

There are two types of filesystems you will need to learn how to make in order to get your Linux multi-partition system up and running are swap and ext2.

–Creating a swap filesystem–

The command for this is mkswap. You have to be root to run this, of course. If you get a “command not found” error, then you need to enter the full path, which is: /sbin/mkswap

The options for mkswapare (ripped from the man page):

Formatting the new disk

Use the following command to format Linux partitions using ext2fs on the new disk:

mkfs.ext2 /dev/hdb1

To check the disk for bad blocks (physical defects), add the -c option just before /dev/hdb1.

If the new disk will have more than one Linux partition, format the other partitions with mkfs.ext2 /dev/hdb2, mkfs.ext2 /dev/hdb3, and so on. Add the -c option if desired.

Note: With older distributions, the command mkfs -t ext2 -c /dev/hdb1 didn’t check for bad blocks under any of Red Hat, Debian or Slackware, contrary to what the man page stated. This has now been fixed.

Recently I encountered a problem when I ftped to my server, I was trying to upload a file that already existed under my username on the server, and I kept getting a 550 error. Which for you newbies out there is a file permission error, telling me that I do not have rights to write over or delete those files under my username.  That made me mad, I didn’t know what was going on I thought my FTP server was messed up.  Then we figured out that the problem could have been who owned the files.  Surely enough, the files were owned by root instead of a pinhead which was the username I was under.  If your files under your username are owned by root then that will allow your file permissions to be limited and you not to be in control of them.  So how do we fix all this?

Building and Installing SSH

For most Unix systems, the installation of SSH is pretty straightforward. Simply download the GNU-zipped tar file from one of the FTP mirror sites listed at http://www.ssh.fi/sshprotocols. (Note: Typically there’s a new version of SSH released every few months.) In order to compile SSH, you need an ANSI C compiler such as gcc. The simplest way to build this software is to do the following:

# ./configure

# make

# make install

The configure script should recognize your system type, discover important information about your build environment, and–if everything checks out–create a corresponding Makefile. The make program uses this Makefile to build the software. The make install directive installs the SSH components and man pages in the right places and generates the initial 1024-bit host key pair (if it doesn’t already exist).