Permission /dev/ttyUSB*

carel · Post by **carel** » 19 Mar 2012, 20:00

Hi

I have searched the forum but could not find anything that helps me.

So here goes.

I have build and installed usb_modeswitch Version 1.2.3
I struggled at first but eventual managed to get everything working.

$ uname -r
2.6.32-24-generic

$ ls -l /dev/gsmmodem
lrwxrwxrwx 1 root root 7 2012-03-18 20:43 /dev/gsmmodem -> ttyUSB3

$ ls -l /dev/ttyUSB3
crw-rw---- 1 root dialout 188, 3 2012-03-18 21:43 /dev/ttyUSB3

My user account is part of the dialout group

$ groups
carel adm dialout cdrom dip plugdev lpadmin admin sambashare

Unfortunately I have to be root (sudo) do use the modem?

$ gammu --identify
Can not open specified file.

$ sudo gammu --identify
Device : /dev/gsmmodem
Manufacturer : QUALCOMM INCORPORATED
Model : unknown (29)
Firmware : P3.2 QCT_21_V30_1_081118_0_H1 1 [Nov 18 2008 12:26:12]
IMEI : 358880020123348
SIM IMSI : +CIMI: 65510119477258

Am I missing something very obvious? or is my installation faulty?

Thanks in advance.

Post by **Josh** » 20 Mar 2012, 09:28

Can you send simple strings to the modem (echo AT >/dev/gsmmodem) ?

Anyway, this problem is not caused by usb_modeswitch.

carel · Post by **carel** » 20 Mar 2012, 18:17

Yes it appears if I can send (echo AT >/dev/gsmmodem)

I tried minicom -D /dev/gsmmodem and this also works.

I will have to investigate my gammu installation.

In any case thanks for the feed back. It has cleared up any doubts I may have had about usb_modeswitch.

carel · Post by **carel** » 20 Mar 2012, 20:09

Hi I sorted it out. It turned out to be that the first time I executed the gammu command I did it as sudo the log it created had permissions 644 and thus my user account had no permission to wright to the log

Post by **Josh** » 20 Mar 2012, 20:28

A typical catch 22 ...