Learn Linux Shell Scripting - Fundamentals of Bash 4.4

Parameter length

We've done a lot of checks in the book so far. One we haven't carried out, however, is on the length of the supplied parameter. What will probably not surprise you at this point is how we can achieve this: with parameter expansion, of course. The syntax is really simple, too:

${#parameter} Parameter length. The length in characters of the value of parameter is substituted. If parameter is * or @, the value substituted is the number of positional parameters.

So, instead of printing ${variable}, which will substitute the value at runtime, we will use ${#variable}, which will give us a number: the number of characters in our value. This might be a little tricky, as things such as whitespaces can also be considered characters. ...