[Linux] #!/bin/sh and #!/bin/bash, what is the difference, combined with code examples and common exception handling

#!/bin/sh and #!/bin/bash, what is the difference, combined with code examples and common exception handling

#!/bin/shBoth and #!/bin/bashare the beginning of the script file, which are used to specify the interpreter of the script file. where #!/bin/shspecifies the Bourne shell interpreter and #!/bin/bashspecifies the Bash shell interpreter.

The Bash shell is an enhanced version of the Bourne shell that supports more features and syntax. Therefore, if you need to use Bash shell-specific syntax or features in your script, you need to use #!/bin/bashto specify the interpreter.

Here is a simple example that demonstrates the difference between the two interpreters:

#!/bin/sh

echo "Hello, world!"

# 使用 Bash 特有的语法
if [[ 1 -eq 1 ]]; then
  echo "1 equals 1"
fi

In the above example, [[ ... ]]the syntax is used, which is specific to the Bash shell. If you use #!/bin/shto specify the interpreter, an error will be reported:

./test.sh: 6: [[: not found

Therefore, the correct approach is to use #!/bin/bashto specify the interpreter.

Common exception handling includes:

1. Interpreter does not exist: If the specified interpreter does not exist, an error will be reported. This can be avoided by checking for the existence of the interpreter.
2. Insufficient permissions: If the script file does not have execution permissions, an error will be reported. You can add execution permission to the script file through chmod +xthe command.
3. Syntax error: If there is a syntax error in the script file, an error will be reported. You can check for syntax errors by executing the script file at the command line.