join

See the current Perl documentation for join.

Here is our local, out-dated (pre-5.6) version:

join - join a list into a string using a separator

join EXPR,LIST

Joins the separate strings of LIST into a single string with fields separated by the value of EXPR, and returns the string. Example:

    $_ = join(':', $login,$passwd,$uid,$gid,$gcos,$home,$shell);

See split.