Determine if a string is empty inside the shell

determine if a string is empty inside the shell Category: Linux shell2011-12-28 23:18 15371 people read reviews (0) favorite report Shell

There are several main ways to do this:

echo "$str" |awk ' {print length ($)} '
Expr Length "$str"
echo "$str" |wc-c
But the third kind of value will be 1 more, maybe the Terminator is also counted.

There are three ways to determine if a string is empty:
If ["$str" = ""]
If [x "$str" = x]
If [-Z ' $str '] (-n is not null)
Note: You have to double quotation marks, or some commands will be error, form a good habit!

Determine if a string is empty inside the shell