Obtain lock

[Kiwinote]

Hello,
I am writing a program which uses commands related to apt. I would like to be able to obtain the lock in /var/lib/dpkg/lock so that the user can't damage their system by running more than one apt program at once. Does anyone have ideas on how to do this?
Thanks,
Kiwinote

[Kiwinote]

Ideas?

[bernied]

It looks like you just need to have the file open.

[bernied]

...but I'm a bit dumb on how you'd do this - would depend on what langugae you're writing in.

It looks like you just need the lsof command to show it as being in use, though

root@shinym:/var/lib/dpkg# lsof /var/lib/dpkg/lock
COMMAND PID USER FD TYPE DEVICE SIZE NODE NAME
adept_man 6789 root 10uW REG 3,65 0 1157275 /var/lib/dpkg/lock

[Kiwinote]

Thanks for the idea, but allas:

kiwinote@Kiwinote:~$ sudo lsof /var/lib/dpkg/lock
COMMAND PID USER FD TYPE DEVICE SIZE NODE NAME
<myprog>5476 root 4r REG 3,4 0 289173 /var/lib/dpkg/lock
synaptic 5629 root 7uW REG 3,4 0 289173 /var/lib/dpkg/lock
Any other ideas? Would it have to do with the difference in FD, whatever that is? I really can't work it out, the file is always empty and even this doesn't work :confused:

BTW I'm writing in c++ and used the following code to open the file:

fstream lock("/var/lib/dpkg/lock",ios::in);
lock.close();

[bernied]

FD=File Descriptor
From man lsof

not that that will necessarily help very much