What is Shell Scripts

Shell scripts are text files that automate a series of UNIX environment-based commands that otherwise must be performed one at a time. Shell scripts are often used to automate command sequences that repeat, such as services that start or stop on system start up or shut down.

Any command that can be performed from the command line, such as ls, can be included in a shell script. Similarly, any command that can be included in a shell script can be performed on the UNIX environment command line.

Users with little or no programming experience can create and run shell scripts. You initiate the sequence of commands in the shell script by simply entering the name of the shell script on a command line.

Determining the Type of Shell to Run a Shell Script

There are several different shells available in the Solaris OS. Two of the most commonly used shells are the Bourne shell and the Korn shell.

To ensure that the correct shell is used to run a shell script, the first line of the script should always begin with the characters #!, followed immediately by the absolute path name of the shell required to run the script. These must be the only characters on the first line of the file.

#!/full-pathname-of-shell

For example:

#!/bin/sh

or

#!/bin/ksh

Comments
Comments are text entries that often provide information about a shell  script. They are inserted into a shell script but have no effect on the script  itself. Comments are ignored by the shell and are solely for the benefit of the  user.
Comments are preceded by the hash (#) character. Whenever the shell  encounters a word beginning with the # character it ignores all text on  that line.
For example:
# this is a comment
ls -l 		# list the files in a directory