shebang

operating system (Or "shebang line", "bang path")

/sh*-bang'/ (From "sharp" and "bang") The magic cookie

"#!" used in Unix to mark the start of a script, e.g. a

shell script or Perl script.

Under Unix, if the first two bytes of an executable file

are "#!", the kernel treats the file as a script rather than

a machine code program. The word following the "!" (i.e.,

everything up to the first whitespace) is used as the

pathname of the interpreter. For example, if the first

line of an executable is

#!/usr/local/bin/perl

the script will be treated as a Perl script and passed as an

argument to /usr/local/bin/perl to be interpreted. Some

variants of Unix also allow one or more parameters to be

passed to the interpreter, for example, you can write

#!/usr/bin/perl -w

and the script will be started as if you typed

/usr/bin/perl -w filename

on the command line. Also, most modern kernels ignore any

whitespace between the "!" and the interpreter pathname. Even

some modern kernels have fairly small limits (e.g. 32) on the

length of line they will accept, making long pathnames and

arguments somewhat unportable.

[Does anyone call this a "magic string"?]

(1998-05-06)