Shell Script in non-prompt mode

[Sammy_2]

How do I get place the script in non-interactive mode so that it automatically answers "y" and hits carriage return after each prompt instead of waiting for a user input. Please look the script below.

===========================================
for i in `vgdisplay -v vgtest| egrep "LV Name"|awk '{print $NF}'`
do
lvreduce $i
done
==============================================

I get the following prompt after before LV removal.
=====================
The logical volume "/dev/vgtest/lvol1" is not empty;
do you really want to delete the logical volume (y/n) :

========================

[Patrick Wallek]

use 'lvreduce -f'.

[Tom Maloy]

It's not the shell script, it's each of the individual commands. So you will need to use the "-f" option for lvreduce, and other options (if available) for other commands. Or else use "expect" or pipe the required characters into the command.

Tom

[Darrell Allen · Accepted solution]

Hi,

For this command, there's the -f option as already pointed out. When the command doesn't have an option, most can be scripted by using "here-document" syntax. You simply redirect standard input from the script. Example:

command <y

something
something else
n
EOF

In this example, "y" is passed as input the first time "command" expects input. The second time, a null response is input (the blank line is just as if you entered CR from the keyboard). The third time "something" is input. And so on...

For here-documents, there are to be no leading spaces for any input line nor the ending "word" (EOF in this example). You can use leading tabs if you specify the here-document by using <<- instead of <<. Also, EOF isn't special. You can use any word. See man sh-posix for more info.

Darrell

[Jean-Louis Phelix]

Hi,

Just for information because you've got some good answers already (-f option of lvreduce and redirecting input using <<), but there is also a funny tool that you can use when you need a lot of 'y' answer. It's 'yes', which sends 'y' followed by a linefeed repeatedly (or any other string if you want). So just pipe it to your script :

yes | rm -i a b

will answer yes to all suppress confirmation (I know that in this case 'rm a b' would be better :^) ).

Or

yes good | foo

will answer good to all foo inputs.

Regards.

[Steven E. Protter]

from the man page.

lvreduce cannot be performed if the volume group is activated in shared mode.

Even if you get feed the y to the program if you try it in certain circumstances it will squawk.

more
lvreduce asks for confirmation before deallocating logical extents if
the -f option is omitted.



redundant post? Perhaps.

Steve

[Sammy_2]

Thanks All.
Jean- your suggestion works on rm command
but when I do a lvremove on LV
y | lvremove /dev/vgmass/lvol1
it gives me "Bad Input Parameter"
Darrell-yours worked perfectly with the EOF script
Steve, Tom, Pat, thanks to all with lvreduce option but I was looking for an option to be used with other commands as well.

[Jean-Louis Phelix]

hi,

Strange, I give you the execution on my system :

/.root# lvcreate -L 12 vg00
Logical volume "/dev/vg00/lvol13" has been successfully created with character device "/dev/vg00/rlvol13".
Logical volume "/dev/vg00/lvol13" has been successfully extended.
Volume Group configuration for /dev/vg00 has been saved in /etc/lvmconf/vg00.conf
/.root# yes | lvremove /dev/vg00/lvol13
The logical volume "/dev/vg00/lvol13" is not empty;
do you really want to delete the logical volume (y/n) : Logical volume "/dev/vg00/lvol13" has been successfully removed.
Volume Group configuration for /dev/vg00 has been saved in /etc/lvmconf/vg00.conf

So it seems to work, but I use 'yes', not 'y'. Anyway it was just for fun because in your case I would also have redirected input using << :^)

Regards.