You can just M-x perl-mode to activate perl mode.

Or, set a easy key to perl-mode. For example,

(global-set-key (kbd "<f8>") 'perl-mode)

Or, you can put add this comment to the first line in the bash file

# -*- mode: perl -*-

then, it'll open with perl mode.

There are other solutions, depends on exactly what you want to do.

You can just M-x perl-mode to activate perl mode.

Or, set a easy key to perl-mode. For example,

(global-set-key (kbd "<f8>") 'perl-mode)

Or, you can put add this comment to the first line in the bash file

# -*- mode: perl -*-

then, it'll open with perl mode.

Or, you can put the following at the bottom

# Local Variables:
# eval: (perl-mode 1)
# End:

Does that answer your question?