Unix

Most of MS-DOS' commands were based on those of Unix and CP/M. 'cd', 'dir', 'clear', and 'echo' are usually found in both. MS-DOS added it's own commands, however, and made some different from those of existing versions of Unix, and no one saw any reason to change the names of existing ones in Unix.

Perl is a scripting language. It is not, however, a shell scripting language because Perl is not a shell program. A shell program is one that usually interacts with a user and provides certain user interface abilities. Perl was not designed for that purpose.

You can certainly program a shell to operate in various fashions. A shell script is usually provided for redundant tasks and series of commands, unattended operation, and so forth.

Perl is a "kitchen sink" of ways to interact with data, databases, networks, and so forth. It is a great language for manipulating text in various ways.

Your question doesn't make a lot of sense, but if the permission is 000 none of the access bits are set and nobody can access the file. However, the root user is "special" in many ways, and depending on the implementation it's possible that root can access it (root can certainly change the permissions to allow him- or herself to access it).

The exact command varies with different Unix or Linux systems, but usually it looks like:

adduser --home /home/jd --shell /bin/bash --group 65535 jd

Check the adduser command on your system for exact details.

It can't be exactly the same name as root; directories in Unix have to be unique, and therefore you can't duplicate the name.

A shell program is the interface between the user (environment) and the operating system (kernel). It allows users to specify commands and requests the operating system to execute them.

An absolute pathname, is the location of a filesystem object relative to the root directory.

absolute pathnames always begin with a slash (/).

With Absolute pathname you have access to complete file system objects such as directories and files.

shutdown -Fr

Use the "system" function: system("Command.exe"); (See: php.net/system)

It uses both techniques.

see related links

Interprocess communication allows one process to send or receive a message to or from another process. Normally, in Unix, processes are in a separate address space and cannot exchange information. With interprocess communication, they are allowed to exchange information to each other.

The output would be 'shell shell' (without the quotes, of course)

The question is a bit vague, since a PID changes with every process, and any user may be attached to that process. Please clarify what you are asking.

ping is a test command. It sends a "ping" to a specified IP which should ACK back, when the ACK is received the message turnaround time is calculated. If the IP fails to respond it times out and reports failure. You can use this command to verify network connectivity, etc.

For Unix/Linux, use the command 'cd /'

For Windows, you can also use the same command or 'cd \'

There are many variations of the useradd command; most standard installations may not have this switch. Please identify which Unix system you are talking about.

In Bell Labs which has its headquarters in New Jersey, but has had other locations.

If you consider all the versions of Mac OS to be a "line", then the latest series, Mac OS X, would generally fit your description. However, it'd be stretching it a bit to call it "recent"; The first version of Mac OS X was released in 1999.

cp, or "copy", makes an exact duplicate of a file and puts it in the specified location. ln instead makes a "link" to the file. The advantage of using ln is that it saves space on the hard drive, and operations applied to the link will affect the target.

Some examples of the Unix find command are "find . -print" or "find /-name foo". One other command could be "find /home/wpollock/foo" or "find /tmp /var/tmp. $HOME -name foo".

Both commands are used to allow two users to communicate on a Unix system when logged in (kind of an early instant messaging system).

The 'write' command causes a line to appear on another user's terminal screen only after the sending user completes the entire line and presses the enter key.

The talk command splits the screen into two segments, allowing the two users to talk at the same time. It sends each character as the user types it, unlike 'write' which only sends complete lines. You can see exactly how quickly a user types with 'talk' but not with 'write'.

The Korn shell is a command interpretor that combines the syntax and abilities of the csh shell and the sh (Bourne) shell. It was designed by David Korn of Bell Labs.