August 19, 2018
Comments in Bash begin with the “#” symbol.
# comments go here
File extension of a Bash script is “.sh”. To run the script in the terminal use the “bash” command. For the script to run, place the following line at the top:
Declare variables by assigning a value to a reference. Bash variables have no data type so they can contain a number, string, or character. The variable is retrieved with the “$”” symbol.
name="Bart Simpson" echo "My name is $name"
Test operators can be used in a Bash script to determine if a file or directory exists. A table of Bash test operators for files is available at tldp.org. The example below demonstrates whether a file named bash-test-file.md exists in the Desktop directory.
if [ -e ~/Desktop/bash-test-file.md ] then echo "file exists" else echo "file does not exist" fi
This example determines whether a directory (folder) named pressure2 exists in the Desktop directory.
if [ -d ~/Desktop/pressure2 ] then echo "folder exists" else echo "folder does not exist" fi