Question

I was going through some shell script tutorials and found the following sample program:

#!/bin/sh
clear
echo "HELLO WORLD"

Can anyone please tell me what the significance of the comment #!/bin/sh at the start is?

Answer 1

It’s called a shebang, and tells the parent shell which interpreter should be used to execute the script.

#!/bin/sh <--------- bourne shell compatible script
#!/usr/bin/perl  <-- perl script
#!/usr/bin/php  <--- php script
#!/bin/false <------ do-nothing script, because false returns immediately anyways.

Most scripting languages tend to interpret a line starting with # as comment and will ignore the following !/usr/bin/whatever portion, which might otherwise cause a syntax error in the interpreted language.