BATwhen present, is automatically executed, so any commands that need to be run to set up the DOS environment may be placed in this file. BAT file set up the system date and time, initialize the DOS environment, load any resident programs or device drivers, or initialize network connections and assignments.
By Vic Laurie Batch files or scripts are small easy-to-write text files that carry out a series of commands. They can be simple enough that even the average home computer user can take advantage of them.
Systems administrators and power users are well aware of the utility of batch files but the average PC user is generally unacquainted with them or is intimidated by the notion of writing or even running a script. This is unfortunate since it means that many are foregoing the use of a powerful tool for carrying out routine or repetitive tasks.
Although batch files can be quite sophisticated and used for complicated network and system administration, they can also be of the utmost simplicity and very brief.
In this article, I will introduce the batch file and discuss some uncomplicated examples that make basic tasks easier. What is a batch file? These are simple text files containing some lines with commands that get executed in sequence, one after the other.
Files of this type are recognized and executed through an interface sometimes called a shell provided by a system file called the command interpreter. Constructing a batch file consists of nothing more than opening any text editor like the accessory Notepad, entering some lines containing commands, and saving the file with an extension BAT or CMD.
In Windows XP, Vista, and 7 there is little practical difference between the two extensions.
Don't use Wordpad or Word unless you are very careful to save all files in pure text format. The commands themselves are often quite simple and there is no need to learn a programming language. Those who wish can explore the intricacies that are available with branching and looping but here I will confine the discussion to some straightforward application to everyday tasks.
The focus will be on saving time and effort for some routine stuff like system housekeeping and simple file management.
Running a batch file is a simple matter of clicking on it. Batch files can also be run in a command prompt or the Start-Run line. In that case, the full path name must be used unless the file's path is in the path environment.
Constructing a batch file In the following discussion it is assumed that the Introductory page and the page on Commands have been read. The first line in a batch file often consists of this command echo offBy default, a batch file will display its commands as it runs.
The purpose of this first command is to turn off this display. The command "echo off" turns off the display for the whole script, except for the "echo off" command itself.
The "at" sign " " in front makes the command apply to itself as well.
This nuance isn't really all that important in the context here but I mention it because it is often seen in scripts. The scripts we will discuss are very brief and omitting this line won't make any great difference.
However, as a matter of good practice, we will enter it in our scripts. Our first batch file example is going to list all the files in a folder and put the list in a new text file.
We will use the directory command "dir" that is discussed on another page. Open Notepad and enter the line " echo off" without quotes. Next enter another line dir "C: This will give us the two-line file echo offdir "C: Be sure that Notepad is saving as "All files" and not as a text file.
See the figure below. Three important points are illustrated in the example script.I'm trying to write a shell script that, when run, will set some environment variables that will stay set in the caller's shell. setenv FOO foo in csh/tcsh, or export FOO=foo in sh/bash only se.
Git always runs inside a bash shell, and uses a number of shell environment variables to determine how it behaves. Occasionally, it comes in handy to know what these are, and how they can be used to make Git behave the way you want it to. Environment variables are not often seen directly when using Windows.
However there are cases, especially when using the command line, that setting and updating environment variables is a .
Nov 30, · This example checks for the existence of the environment variable "VARIABLE." If VARIABLE does not exist, the statement is true and control of the batch file jumps to the MODULE section.
If the statement is not true, that is, the VARIABLE variable does exist, program control skips to the next line of the batch file and continues. The MySQL server maintains many system variables that configure its operation. Each system variable has a default value.
System variables can be set at server startup using options on the command line or in an option file. Windows Environment Variables. Environment variables are mainly used within batch files, they can be created, modified and deleted for a session using the SET command.
To make permanent changes, use SETX Variables can be displayed using either SET or ECHO.. Variables have a percent sign on both sides: %ThisIsAVariable% The .