topic Re: call shell script with . ./myscript.sh in Operating System - HP-UX

call shell script with . ./myscript.sh

Leo The Cat — Thu, 20 Dec 2007 15:21:21 GMT

Hi

Why sometimes some scripts needs to be call with the . ./myscript.sh syntax and sometimes with the ./myscript.sh ?

Thanks in advance
Regards
Den

Re: call shell script with . ./myscript.sh

MarkSyder — Thu, 20 Dec 2007 15:23:41 GMT

The extra . causes the script to run without invoking a new shell.

Mark Syder (like the drink but spelt different)

Re: call shell script with . ./myscript.sh

Pete Randall — Thu, 20 Dec 2007 15:25:38 GMT

And without the extra ., it simply means to look in the current directory ($PWD) to find "myscript.sh.

Pete

Re: call shell script with . ./myscript.sh

Pete Randall — Thu, 20 Dec 2007 15:26:58 GMT

That was poorly worded.

In either case, the single period immediately preceding /myscript.sh means to look in the current directory.

Pete

Re: call shell script with . ./myscript.sh

Leo The Cat — Thu, 20 Dec 2007 15:36:57 GMT

Hi

What could be the consequences to launch another shell ?

Regards
Den

Re: call shell script with . ./myscript.sh

Sandman! — Thu, 20 Dec 2007 15:41:25 GMT

Read the manpage of sh-posix(1) for details. Relevant portion posted below:

sh-posix(1)
.
.
% . file [arg]...

(period) Read and execute commands from file and return. The
commands are executed in the current shell environment. The
search path specified by PATH is used to find the directory
containing file. If any arguments arg are given, they become the
positional parameters. Otherwise, the positional parameters are
unchanged. The exit status is the exit status of the last
command executed.

Re: call shell script with . ./myscript.sh

James R. Ferguson — Thu, 20 Dec 2007 15:46:35 GMT

Hi Den:

The dot-space-filename (whether or not the filename contains a relative path of "./" means that you want to *source* or read the contents of the file into your *current* environment without starting a new shell (and thus losing the variable values).

Sourcing is done to pass environmental variables defined in a file into the environment of another:

# cat mythings
#!/usr/bin/sh
export NAME=Den

# cat someshell
#!/usr/bin/sh
. ./mythings
echo "I am ${NAME}"
exit 0

To see the difference, run 'someshell'; then change the line that reads:

. ./mythings

TO:

./mythings

...and run 'someshell' again.

Regards!

...JRF...

Re: call shell script with . ./myscript.sh

Dennis Handly — Fri, 21 Dec 2007 08:29:08 GMT

Typically scripts are not sourced and need to be executable. Files that are sourced are typically the shell env files (for aliases and functions) and just need to be readable.

Re: call shell script with . ./myscript.sh

Leo The Cat — Tue, 06 May 2008 00:20:05 GMT

Answer was various and good.