Pass Arguments to Command from Shell Script

Shell Programming and Scripting
1

Hi all,

I am working on a project, in which I have to connect to Bluetooth low energy device. I am able to connect and do data transfer from command line. But I want to do from script
Here is my script

#!/bin/bash
#sudo hcitool -i hci0 lescan
sleep 1
sudo hcitool -i hci0 lecc --random EA:74:48:D5:52:6B
sleep 1
sudo gatttool -i hci0 -b EA:74:48:D5:52:6B --interactive
sleep 1
echo connnect //this command should be passed as arg to gatttool command
sleep 1 
char-write-cmd 0x0013 FF14
done

Here is screen shot when I run gatttool from command line

Here is the screen shoot when I run from script

In the above figure I have to pass command "connect" where there is red arrow from the script. I tried echo. But its not working

So please help me how to pass command
:confused:

2

You might want to remove the "-- interactive" option from the command in the script.

Given the tool reads from stdin, you could try piping or redirection:

echo connect | sudo gatttool ...

or (if your bash is recent enough)

sudo gatttool <<<  connect
3

Hi,

Option --interactive is must. With out that option neither it would not connect to the device nor it will not accept gatttool as valid command.

So any other way?

4

Did you read the entire post?

5

Hi,

I have tried other option also.
Here is script

sudo hcitool -i hci0 lecc --random EA:74:48:D5:52:6B
sleep 1
sudo gatttool -i hci0 -b EA:74:48:D5:52:6B --interactive <<< connect

When i run above script ths is error I am getting

sh ble_connect_write.sh 
[sudo] password for embdesnithin: 
Connection handle 70
ble_connect_write.sh: 7: ble_connect_write.sh: Syntax error: redirection unexpected
6

I think the biggest problem is here is the misconception about what sudo does and what it doesn't:

sudo will run a command as another user (usually as root), but: it is NOT a shell and neither it is a shell replacement!

I wonder why the user account you use to run the script is not allowed to run the commands within the script. If the commands are privileged in nature then use a privileged user which can run them natively. call the whole script via sudo instead of embedding sudo-enabled calls into the script.

If you really need to do it the way you tried use su instead of sudo and use sudo only to call the script:

#! /bin/sh
[...]
su - <user> -c <your command along with options>
[...]

user@sys # sudo <scriptname>

I hope this helps.

bakunin

7

I am using bash instead of sh.

I tried "su". But of no use.
script:

su - embdesnithin --command hcitool -i hci0 lecc --random EA:74:48:D5:52:6B
sleep 1
su - embdesnithin --command gatttool -i hci0 -b EA:74:48:D5:52:6B -I <<< connect
sleep 1

Error:

embdesnithin@embdesnithin:~$ sudo sh ble_connect_write.sh 
su: invalid option -- 'i'
Usage: su [options] [LOGIN]

Options:
  -c, --command COMMAND         pass COMMAND to the invoked shell
  -h, --help                    display this help message and exit
  -, -l, --login                make the shell a login shell
  -m, -p,
  --preserve-environment        do not reset environment variables, and
                                keep the same shell
  -s, --shell SHELL             use SHELL instead of the default in passwd

ble_connect_write.sh: 7: ble_connect_write.sh: Syntax error: redirection unexpected
8

You might have an easier time getting this to work if you create a shell script as root that does what you want. Then set it up in sudo to be so that certain user can run it with sudo, but not edit it.

9

This is what i said at first. IMHO this would solve all the troubles once and for all.

I suppose this is just a matter of correct quoting:

su - embdesnithin -c "hcitool -i hci0 lecc --random EA:74:48:D5:52:6B"

Note the double quotes around the command, analoguous for the other lines.

You should, btw., not use these long options, i.e. "--command" instead of "-c". This only works with the GNU versions of commands, not with the standard command. This way you unnecessary limit the portability of your script.

"/bin/sh" is on most systems a call to the systems default shell which i used as a stand-in. As you seem to work on a Linux-System this should call a bash .

I hope this helps.

bakunin