General Form:

strcmp _flag $string1 "string2"

The command compares two strings, either given by a variable (string1) or as a string in quotes (`string2'). _flag is set as an output variable to '0', if both strings are equal. A value greater than zero indicates that the first character that does not match has a greater value in str1 than in str2; and a value less than zero indicates the opposite (like the C strcmp function).