Free derivatives of Unix can be easily downloaded via the Internet. This sets Unix apart from other proprietary operating systems like Microsoft Windows.
The different versions of Unix and Unix-like operating systems available for download include FreeBSD, OpenBSD, Red Hat Fedora Linux, Debian Linux, Ubuntu Linux, and Sun Solaris.
Note that if you are new to Unix or Linux, you can still try these operating systems by using virtual machines, without worrying about your existing data or...
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List Logged In Unix Users
Unix has many commands to list users who are logged in.
These commands include `w`, `who`, and `users`:
$ w
9:51PM up 99 days, 5:39, 2 users, load averages: 0.83, 0.90, 0.90
USER TTY FROM LOGIN@ IDLE WHAT
will p0 c-66-164-235-73. 8:11AM - w
spencer p3 c-66-164-235-73. 8:26PM 1:24 pine
$ who
will ttyp0 Jul 26 08:11 (66.164.235.73)
spencer ttyp3 Jul 26 20:26...
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A signal is a message which can be sent to a running process.
Signals can be initiated by programs, users, or administrators.
For example, to the proper method of telling the Internet Daemon (inetd) to re-read its configuration file is to send it a SIGHUP signal.
For example, if the current process ID (PID) of inetd is 4140, we would type:
kill -SIGHUP 4140
Another common use of signals is to stop a running process. To stop the inetd process completely, we would use this command:
kill...
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All of us like safety. The safety of our confidential information is always a special concern. It's always a good feeling when you know that everything is secure. With that said, information protection is a necessity and can be useful to companies and individuals who care about the confidentiality of their intellectual property. People who want their e-mails kept confidential and their e-mail attachments readable only to the intended recipient can appreciate information...
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Solaris makes it unreasonably difficult to change the hostname of an installed server.
To change the hostname on a Solaris system, you should edit all of these files:
- /etc/hosts
- /etc/nodename
- /etc/hostname.*
- /etc/net/ticlts/hosts
- /etc/net/ticots/hosts
- /etc/net/ticotsord/hosts
- /etc/inet/ipnodes
You should then reboot the server to test your changes and ensure that they operate correctly. |
umask is a Unix shell built-in command which automatically sets file permissions on newly created files.
The umask command can be confusing to use, because it does work as a mask. In other words, you set the permissions that you do not want in the umask.
To calculate permissions which will result from specific umask values, subtract the umask from 777. Note, however, that files are not usually created with the execute permission by default, so the final permissions for files will omit...
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To change an IP address on a Solaris system immediately, use the `ifconfig` command.
The syntax for `ifconfig` is:
ifconfig <interface> <ip address> <netmask> <broadcast address>
If you don't know the names of your network interfaces, use the `ifconfig -a` command to list all of the available network interfaces.Permanently Change an IP Address on Solaris
To make this change permanent, you will need to edit one or more Solaris configuration files. If you do not...
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If you have a small business or small enterprise that requires a file server, one of the ways you can save thousands upon thousands of dollars per year is to set up a Linux file server. Linux is an open source software platform that in many ways is just as good as or better than other types of platforms including Microsoft and Sun.
For small businesses and enterprises that require a file server, you can save immensely on the costs related to maintenance, support, licensing fees and...
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Unix users write, edit, list, and remove cron jobs using the `crontab` command.
`crontab -e` takes you into your default editor to edit your crontab entries.
`crontab -l` lists your crontab.
`crontab -r` removes your crontab.crontab Security
If the cron.allow file exists, then you must be listed in that file in order to be allowed to use the `crontab` command. If the cron.allow file does not exist but the cron.deny file does exist, then you must not be listed in the cron.deny file in...
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To change your Unix password, use the `passwd` command.
Here is an example of the user "will" changing his Unix password:
$ passwd
Changing local password for will
Old Password:
New Password:
Retype New Password:
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