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Sometime Today, Rajen Parekh assembled some asciibets to say:
> "Cannot open /dev/ttyS1: Device or resource busy". It seems that a
> non-root user cannot access modem. The /dev/ttyS1 appears as,
Your dial out program should actually be setuid root, but you can change
the permissions anyway. I suggest you put it into your rc.local because
some programs have the tendency of changing it back to 600.
> crw------- 1 root tty 4, 65 June 26 14:20 ttyS1
>
> What does "c" mean? Can/Should I change the mode to 0644 for other users
The c means that it is a character special file. In linux, you have three
types of special files:
c - character special
These are devices with sequential access that are read byte (character) by
byte. Random access not possible.
Serial port, /dev/null, /dev/zero, terminals are all character special
b - block special
These are devices that have block access. You can reposition the pointer
to any point within the block. This allows random access.
disk drives etc are block special.
p - named pipes or fifos
A fifo - like the name suggests - is a first in first out device. Data is
stored in it only until some process reads from it. You cannot seek
forward or backward into a pipe. It's like the normal pipe that you use
to send the output of one process as the input of a second process:
ls | wc -l
except these pipes have names and can be used by any process.
Certain system processes use fifos to store state data that other
processes can read. You could make your .signature file a fifo and have
one process write to it every 5 seconds, but I don't recommend that.
There's also Unix Domain Sockets - but you should read a book for that.
Philip
--
Trying to be happy is like trying to build a machine for which the only
specification is that it should run noiselessly.
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