If you face the udev as the last resort, as dread crazy, then they really will scare you. If you look to a simple rule, and try to expand it, you will see udev is simple, more simple than bash scripting.
In http://www.reactivated.net/writing_udev_rules.html there is a complete (and long) tutorial on the matter. Enjoy! Mauro http://mauro.limeiratem.com - registered Linux User: 294521 Scripture is both history, and a love letter from God. On Thu, Sep 2, 2010 at 5:20 AM, Vlacil, Radek <[email protected]> wrote: > Thanks very much for your answer. > > I thought it is possible to do it by udev. I was just little bit scared of > that crazy udev rules :D and I had that as the last resort. > > Radek Vlacil > > > CA CZ, s.r.o. Prague 4, Chodov, V Parku 2316/12, postal code 148 00, > Identification No. 25694073, registered in the Commercial Register > maintained by the Municipal Court in Prague in Section C, Insert No. 61808" > > -----Original Message----- > From: Linux on 390 Port [mailto:[email protected]] On Behalf Of > Sebastian Ott > Sent: Wednesday, September 01, 2010 18:44 > To: [email protected] > Subject: Re: Tapes 34xx detection > > Hi, > > On Wed, 1 Sep 2010, Vlacil, Radek wrote: > > Is there any way how to detect in an application that 34xx tape was > > attached through ccw. In other words, detect that new directory for that > > tape appeared in /sys/bus/ccw/devices/ and that it is ready for > > "chccwdev -e". I would like to have a program that tracks whether any > > tape was attached or detached and I was wondering whether there is > > another option than "try-to-open and wait" loop. > > when a device is added/removed to/from linux the kernel will create > "uevents" to inform userspace about these events. a daemon called > udevd receives these events and triggers some actions. the actions > can be specified by udev scripts. > > so it should be possible to extend your distributors udev scripts > (or write your own) to e.g. write a logfile if a tape device is attached. > > if i monitor uevents i get: > # udevmonitor --env > ... > UEVENT[1283357379.294644] add /devices/css0/0.0.0014/0.0.1001 (ccw) > ACTION=add > DEVPATH=/devices/css0/0.0.0014/0.0.1001 > SUBSYSTEM=ccw > CU_TYPE=3990 > CU_MODEL=E9 > DEV_TYPE=3390 > DEV_MODEL=0A > MODALIAS=ccw:t3990mE9dt3390dm0A > SEQNUM=1643 > ... > UEVENT[1283357406.102060] remove /devices/css0/0.0.0014/0.0.1001 (ccw) > ACTION=remove > DEVPATH=/devices/css0/0.0.0014/0.0.1001 > SUBSYSTEM=ccw > CU_TYPE=3990 > CU_MODEL=E9 > DEV_TYPE=3390 > DEV_MODEL=0A > MODALIAS=ccw:t3990mE9dt3390dm0A > SEQNUM=1644 > > for attaching/detaching devices (no tape, but you should get > the idea...) > > regards > sebastian > > > > These are messages in the system log which describes events I'd like to > > trap: > > > > > > > > kernel: crw_info : CRW reports slct=0, oflw=0, chn=0, rsc=3, anc=1, > > erc=4, rsid=5 > > > > kernel: TAPE_CORE: tape device 0.0.0186 found > > > > kernel: TAPE_CORE: (0.0.0186): Tape has been mounted > > > > kernel: TAPE_BLOCK: Detecting media size... > > > > kernel: TAPE_BLOCK: Found 2 blocks on media > > > > kernel: TAPE_CORE: (0.0.0186): Tape is unloaded > > > > kernel: crw_info : CRW reports slct=0, oflw=0, chn=0, rsc=3, anc=1, > > erc=4, rsid=5 > > > > > > > > Radek Vlacil > > > > > > > > > > ---------------------------------------------------------------------- > > For LINUX-390 subscribe / signoff / archive access instructions, > > send email to [email protected] with the message: INFO LINUX-390 or > visit > > http://www.marist.edu/htbin/wlvindex?LINUX-390 > > ---------------------------------------------------------------------- > > For more information on Linux on System z, visit > > http://wiki.linuxvm.org/ > > > > ---------------------------------------------------------------------- > For LINUX-390 subscribe / signoff / archive access instructions, > send email to [email protected] with the message: INFO LINUX-390 or > visit > http://www.marist.edu/htbin/wlvindex?LINUX-390 > ---------------------------------------------------------------------- > For more information on Linux on System z, visit > http://wiki.linuxvm.org/ > > ---------------------------------------------------------------------- > For LINUX-390 subscribe / signoff / archive access instructions, > send email to [email protected] with the message: INFO LINUX-390 or > visit > http://www.marist.edu/htbin/wlvindex?LINUX-390 > ---------------------------------------------------------------------- > For more information on Linux on System z, visit > http://wiki.linuxvm.org/ > ---------------------------------------------------------------------- For LINUX-390 subscribe / signoff / archive access instructions, send email to [email protected] with the message: INFO LINUX-390 or visit http://www.marist.edu/htbin/wlvindex?LINUX-390 ---------------------------------------------------------------------- For more information on Linux on System z, visit http://wiki.linuxvm.org/
