Shell脚本编程学习入门：Shell编程基础（国外英文资料）.docVIP

Shell脚本编程学习入门：Shell编程基础（国外英文资料） Shell script programming learning portal is this article to introduce the content, we can use any text editor, such as gedit, kedit, emacs, vi to write a Shell script, it must start with the following line in the first line of the file (required) : #! / bin/sh ... Note: it is best to use ! / bin/bash instead of! / bin/sh , if you use tc shell instead of TCSH. Sign #! The program used to tell the system to execute the sell script, this example USES/bin/sh. After editing is finished and saved, if you want to execute the shell script, you must first make it executable: Chmod + x filename After that, you can execute the shell script under the directory where the shell script is located. Some special symbols in the Shell [a] The shell to the function If youve written a more complex shell script, youll find that the same code is likely to be used in several places, and it will be handy if you use a function. The function looks like this: Functionname () { Inside the body $1 is the first argument given to the function # $2 the second... The body } You need to declare the function at the beginning of each script. Below is a shell script called xtitlebar that changes the name of the terminal window. This USES a function called help, which is used twice in the shell script: #! / bin/sh # vim: set sw = 4 ts = 4 et: Help () { The cat HELP Xtitlebar -- change the name of an xterm, gnome-terminal or kde konsole USAGE: xtitlebar [-h] string_for_titelbar OPTIONS: - h help text EXAMPLE: xtitlebar CVS HELP The exit 0 } In case of error or if-h is given we call the function help: [-z $1] [ $1 = -h ] help Send the escape sequence to change the xterm titelbar: Echo - e 33] 0; $107 # Providing help in shell scripts is a good programming habit that allows other users (and themselves) to use and understand scripts. Command line arguments Weve seen $* and $1, $2... Special variables such as $9, these special variables contain the parameters that the user e