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chage changes the number of days between password changes and the date of the last password change. This information is used by the system to determine when a user must change her password. The chage command is restricted to the root user, except for the -l option, which may be used by an unprivileged user to determine when her password or account is due to expire.
In Vi or Vim, use the forward slash </> to search. Then type in your search string and hit <Enter>. You can navigate through occurrences of your search string using <n> to move forward and <N> to move backwards. Below is an example search for the string ‘array’.
Normally we will set the hostname of a system during the installation process. Many peoples don’t care about this, and don’t change the hostname even if for example this was set to something really stupid by the datacenter that installed the system (most likely they will set this to “debian” on any debian installation, etc). For me, it is important to see on each one of the ssh screens I will have open at any time a different hostname that is relevant and will give me quickly the information on what system I am logged in.
Emacs is a class of text editors that have an extensive set of features and that are popular with computer programmers and other technically proficient computer users.
GNU Emacs, a part of the GNU project, is under active development and is the most popular version. The GNU Emacs manual describes it as “the extensible, customizable, self-documenting, real-time display editor.” It is also the most portable and ported of the implementations of Emacs. As of March 2008, the latest stable release of GNU Emacs is version 22.2. Emacs should be included in most distro’s or easily installable from your distro’s repo’s.
shutdown -h now
halt
poweroff
init 0
All of these does the same thing: turns your computer off.
Rebooting Linux
Use the shutdown command with the parameter -r (reboot):
shutdown -r now
There is some behavior of your Linux Operating System which is easy to change, but not too common to know how.
The things you can change are:
This qref is written for a semi-knowledgable UNIX user who has just come up against a problem and has been advised to use awk to solve it. Perhaps one of the examples can be quickly modified for immediate use.
So you learned how to write your own iptables, unfortunately if you got it configured just the way you want and you reboot, your rules are lost. These few steps will correct that in no time.
The /proc directory is a strange beast. It doesn’t really exist, yet you can explore it. Its zero-length files are neither binary nor text, yet you can examine and display them. This special directory holds all the details about your Linux system, including its kernel, processes, and configuration parameters. By studying the /proc directory, you can learn how Linux commands work, and you can even do some administrative tasks.
Under Linux, everything is managed as a file; even devices are accessed as files (in the /dev directory). Although you might think that “normal” files are either text or binary (or possibly device or pipe files), the /proc directory contains a stranger type: virtual files. These files are listed, but don’t actually exist on disk; the operating system creates them on the fly if you try to read them.
Most virtual files always have a current timestamp, which indicates that they are constantly being kept up to date. The /proc directory itself is created every time you boot your box. You need to work as root to be able to examine the whole directory; some of the files (such as the process-related ones) are owned by the user who launched it. Although almost all the files are read-only, a few writable ones (notably in /proc/sys) allow you to change kernel parameters. (Of course, you must be careful if you do this.)
