a shell script question

[nubalci]

Hi,
When I type
synclient TouchPadOff=1
this disables touchpad.
But if I put the following two lines in a script file as follows:
#!/bin/bash
synclient TouchPadOff=1
it doesn't work (just no effect). What may be the problem, and what do you think would solve it?
Thank you.

[cavh]

Is the script executable?


chmod u+x /path/to/your/script

If the path is outside of your home folder, you may need to sudo it:


sudo chmod u+x /path/to/your/script

[nubalci]

Is the script executable?


chmod u+x /path/to/your/script

If the path is outside of your home folder, you may need to sudo it:


sudo chmod u+x /path/to/your/script

Yes, it is executable and on the path. It runs without error. It just doesn't work, whereas if I type what's in the script in the terminal box it works.

[amauk]

sounds like a permissions problem
Are you running the script as root, or as a normal user?

I don't own a laptop, but it seems unlikely that unprivileged users could disable a piece of hardware

[nubalci]

sounds like a permissions problem
Are you running the script as root, or as a normal user?

I don't own a laptop, but it seems unlikely that unprivileged users could disable a piece of hardware

I don't dispute what you say, but no, I don't sudo, and it just works. I started to think that it is some sort of timing issue. I just hope it isn't something more serious. The reason is that if you run the script enough many times (3 or 4 maybe) it eventually works. And I also discovered that sometimes this may be needed when one directly works at the terminal box, too. So, I don't know for sure, but it looks like some messages are not making it to some sort of queue.

[amauk]

I don't dispute what you say, but no, I don't sudo, and it just works. I started to think that it is some sort of timing issue. I just hope it isn't something more serious. The reason is that if you run the script enough many times (3 or 4 maybe) it eventually works. And I also discovered that sometimes this may be needed when one directly works at the terminal box, too. So, I don't know for sure, but it looks like some messages are not making it to some sort of queue.

Well, again no experience with laptop touchpads
but you could do something like this
(assuming that synclient exits 0 on success)


#!/bin/bash

COUNTER=0
synclient TouchPadOff=1

while [ "$?" -ne 0 ] && [ "$COUNTER" -lt 10 ]; do
sleep 1
synclient TouchPadOff=1
COUNTER=$(expr "$COUNTER" + 1)
done

This will run synclient until either success or 10 failures

[phrostbyte]

Do you plan on running this script at startup?

[nubalci]

Do you plan on running this script at startup?

No, I will run the script, or just type in the command when the touchpad becomes a nuisance. Not at startup.

My first impression was that it had something to do with script file / direct typing, but sure enough this seems not to be the case after trying it many times. The same anomaly can be observed in both cases. It nay have something to do how synclient works, not sure...

[Some Penguin]

What did you name the script, and how are you running it?

[Geek10]

Hi nubalci,

Would you mind posting your whole shell script? You see, I'm possibly going to need one for the first time myself (for some other bit of code).

And whether you consent or not to posting it, were there any particularly helpful resources on writing your shell script code? I'm only a beginner at Unix coding, so anything would be gratefully received!!:-?

Thanks

[pbrane]

try /usr/bin/synclient. you probably need to path in a shell script.

[donwinchell]

I have looked, and looked, can someone please tell me the purpose of the

#!/bin/bash .. ?

line at the beginning of a script. - I have found it is not actually needed.

another one

sometime it seems necessary to put ./ in front of a script to get it to run and sometimes it does not seem necessary what is the ./ about ?

and what is .sh at the end? does it DO anything or just identify the file as a script?
(and yes, I AM making scripts executable)


I have been building and using scripts for a while (a year?) and they work and do useful things for me, but every time I build a new one I seem to have to struggle with these issues. nothing critical here, just some quandaries. Any one with some knowledge and spare time to answer this would be greatly appricieated.

thanks.

[Vox754]

I have looked, and looked, can someone please tell me the purpose of the

#!/bin/bash .. ?

line at the beginning of a script. - I have found it is not actually needed.

That line is called a "shebang". You can read for more information by searching for that term on the Internet.
It defines an interpreter with which to run the script.

You can run a script explicitly by using its interpreter:


bash file.sh
perl file.pl
tclsh file.tcl
python file.py

But if you include the shebang, the system will use the appropriate interpreter automatically.

Respectively


#!/bin/bash
#!/usr/bin/perl
#!/usr/bin/tclsh
#!/usr/bin/python

will allow you to call


file.sh
file.pl
file.tcl
file.py




another one

sometime it seems necessary to put ./ in front of a script to get it to run and sometimes it does not seem necessary what is the ./ about ?

For security purposes, an executable (including a script) will be run only if it is in a directory listed by the $PATH variable.


echo $PATH

/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin:/usr/games


Additionally you can run the executable giving its path, either the full path or a relative path.


/opt/program/bin/executable
../dir/bin/executable


By using "./executable" you are giving the path of the executable in the current directory, which is simply the dot "."



and what is .sh at the end? does it DO anything or just identify the file as a script?
(and yes, I AM making scripts executable)

A file extension, such as ".sh", is not needed in Linux at all. It is only for the convenience of the user. Many scripts are given with an extension to identify them, but others are not. This gives the impression that they are binaries, when in fact they are not. However, this distinction is not necessary. The only requirement is that it must be able to execute.

For example, the command "firefox", is not a binary executable, it's just a shell script which sets up some options and thens calls the real executable.


file /usr/bin/firefox
/usr/bin/firefox: symbolic link to `../lib/firefox-3.6.11/firefox.sh'

file /usr/lib/firefox-3.6.11/firefox.sh
/usr/lib/firefox-3.6.11/firefox.sh: POSIX shell script text executable




I have been building and using scripts for a while (a year?) and they work and do useful things for me, but every time I build a new one I seem to have to struggle with these issues. nothing critical here, just some quandaries. Any one with some knowledge and spare time to answer this would be greatly appricieated.

thanks.
I am surprised that you have been writing scripts for a while and do not know the basics.

[donwinchell]

thanks for your kind explanations.
I guess the reason I have never learned the basics is that my objective has not been to learn to write scripts but just to accomplish some other business objective.
I appreciate your time and explanations.