How to check the first character of a string in Bash
In this tutorial, we are going to learn about how to check the first character of a string in Bash or UNIX shell.
Consider, we have the following string:
url="/src/imgs/car.png"
Now, we need to check if a first character is /
in the above string; we need to return 1
else we need to return 0
.
Checking the first character
To check the first character of a string in the bash shell, we can use the substring expansion syntax {$string::length}
.
length: The number of characters we need to extract from a string.
Here is an example:
url="/src/imgs/car.png"
if [[ ${url::1} == "/" ]]
then
echo 1;
else
echo 0; fi
Output:
1
Similarly, you can also check the first two characters of a string like this:
url="/src/imgs/car.png"
if [[ ${url::2} == "/s" ]]
then
echo 1;
else
echo 0; fi
Output:
1