On Monday 11 July 2005 01:24 pm, Krzysztof wrote: > > I still have a strange problem with owfs, sometimes I can not read files - > just after I disconnect 18b20 from 1 wire network, its "address" directory > (cache) still exists but reading the "temperature" file is impossible -> mc > gives error and crashes :-) > > File exists (I also did test -e, test -s to check it) however I can't read > it :-) > I suspect you can read the "uncached" directory to get a current view of the devices.
There is a trade-off between speed and response to changes. The 1-wire bus is (relatively) slow. For applications where the bus contents change rarely, you can avoid a rescan of the bus by not using the "uncached" directory. If you are recording data values intermittently, you probably want to scan the bus at the start of each sample period, then read uncached values for the database. Here is a simple example (whish says two things, it's hot, and they are pretty accurate!): # x=/mnt/1wire/uncached/*; for y in $x; do echo "$y: `cat $y/temperature`"; \ done cat: /mnt/1wire/uncached/01.0683C9090000/temperature: No such file or directory /mnt/1wire/uncached/01.0683C9090000: cat: /mnt/1wire/uncached/05.5ADD1E000000/temperature: No such file or directory /mnt/1wire/uncached/05.5ADD1E000000: cat: /mnt/1wire/uncached/05.DD011F000000/temperature: No such file or directory /mnt/1wire/uncached/05.DD011F000000: cat: /mnt/1wire/uncached/09.BCCA79030000/temperature: No such file or directory /mnt/1wire/uncached/09.BCCA79030000: /mnt/1wire/uncached/10.003054000800: 33.0625 /mnt/1wire/uncached/10.044954000800: 33.125 /mnt/1wire/uncached/10.052854000800: 33.0625 /mnt/1wire/uncached/10.074D54000800: 33.125 /mnt/1wire/uncached/10.0D2B54000800: 33.125 /mnt/1wire/uncached/10.101454000800: 33.0625 /mnt/1wire/uncached/10.101554000800: 32.9375 /mnt/1wire/uncached/10.164F54000800: 33.0625 /mnt/1wire/uncached/10.182654000800: 33.1875 /mnt/1wire/uncached/10.1D1554000800: 33.125 /mnt/1wire/uncached/10.234254000800: 33.125 /mnt/1wire/uncached/10.2C1B54000800: 33.125 /mnt/1wire/uncached/10.2D4154000800: 33.0625 /mnt/1wire/uncached/10.301A54000800: 33.125 /mnt/1wire/uncached/10.311154000800: 33.125 /mnt/1wire/uncached/10.39756B000800: 33.25 /mnt/1wire/uncached/10.3C1F54000800: 33.0625 /mnt/1wire/uncached/10.401D54000800: 33.0625 /mnt/1wire/uncached/10.414354000800: 33.125 /mnt/1wire/uncached/10.42916B000800: 33.125 /mnt/1wire/uncached/10.483354000800: 33.0625 /mnt/1wire/uncached/10.4A2D54000800: 33.0625 /mnt/1wire/uncached/10.4A4454000800: 33.125 /mnt/1wire/uncached/10.4E4C54000800: 33.125 /mnt/1wire/uncached/10.552954000800: 33.125 /mnt/1wire/uncached/10.584E54000800: 33 /mnt/1wire/uncached/10.5A3F54000800: 33.0625 /mnt/1wire/uncached/10.5E1B54000800: 33.0625 /mnt/1wire/uncached/10.601454000800: 33.0625 /mnt/1wire/uncached/10.602454000800: 33.0625 /mnt/1wire/uncached/10.602E54000800: 33.0625 /mnt/1wire/uncached/10.611154000800: 33.125 /mnt/1wire/uncached/10.641654000800: 33.125 /mnt/1wire/uncached/10.653E54000800: 33.0625 /mnt/1wire/uncached/10.674E54000800: 33.0625 /mnt/1wire/uncached/10.6F3F54000800: 33.25 /mnt/1wire/uncached/10.711C54000800: 33.125 /mnt/1wire/uncached/10.792F54000800: 33.1875 /mnt/1wire/uncached/10.793E54000800: 33.125 /mnt/1wire/uncached/10.7E3754000800: 33.125 /mnt/1wire/uncached/10.801754000800: 33.0625 /mnt/1wire/uncached/10.821454000800: 33.1875 /mnt/1wire/uncached/10.892254000800: 33.0625 /mnt/1wire/uncached/10.894F54000800: 33.0625 /mnt/1wire/uncached/10.8B3954000800: 33.125 /mnt/1wire/uncached/10.904154000800: 33.125 /mnt/1wire/uncached/10.904954000800: 33.125 /mnt/1wire/uncached/10.974F54000800: 33.125 /mnt/1wire/uncached/10.9A2F54000800: 33.125 /mnt/1wire/uncached/10.9A9E3C000800: 33.125 /mnt/1wire/uncached/10.9B2D54000800: 33.0625 /mnt/1wire/uncached/10.9C4654000800: 33.0625 /mnt/1wire/uncached/10.9D4154000800: 33.0625 /mnt/1wire/uncached/10.A44E54000800: 33.0625 /mnt/1wire/uncached/10.A53654000800: 33.1875 /mnt/1wire/uncached/10.A73A54000800: 33.125 /mnt/1wire/uncached/10.AA4D54000800: 33.125 /mnt/1wire/uncached/10.AC2754000800: 33.125 /mnt/1wire/uncached/10.AD1A54000800: 33.125 /mnt/1wire/uncached/10.B14154000800: 33.125 /mnt/1wire/uncached/10.B64054000800: 33.125 /mnt/1wire/uncached/10.B72E54000800: 33.0625 /mnt/1wire/uncached/10.B74754000800: 33.1875 /mnt/1wire/uncached/10.B83754000800: 33.125 /mnt/1wire/uncached/10.BB1754000800: 33.1875 /mnt/1wire/uncached/10.BE2254000800: 33 /mnt/1wire/uncached/10.C24654000800: 33.125 /mnt/1wire/uncached/10.C44154000800: 33.125 /mnt/1wire/uncached/10.C64354000800: 33.0625 /mnt/1wire/uncached/10.C74E54000800: 33.125 /mnt/1wire/uncached/10.CE4B54000800: 33.0625 /mnt/1wire/uncached/10.CF1F54000800: 33.0625 /mnt/1wire/uncached/10.D03754000800: 33.125 /mnt/1wire/uncached/10.D54B54000800: 33.125 /mnt/1wire/uncached/10.D7AB3C000800: 33.0625 /mnt/1wire/uncached/10.DA4754000800: 33.0625 /mnt/1wire/uncached/10.DB2754000800: 33.0625 /mnt/1wire/uncached/10.DC3D54000800: 33.125 /mnt/1wire/uncached/10.DC4454000800: 33 /mnt/1wire/uncached/10.E04654000800: 33.0625 /mnt/1wire/uncached/10.E12954000800: 33.0625 /mnt/1wire/uncached/10.EB1254000800: 33.125 /mnt/1wire/uncached/10.ED3554000800: 33.125 /mnt/1wire/uncached/10.EF2E54000800: 33.1875 /mnt/1wire/uncached/10.F03D54000800: 33.125 /mnt/1wire/uncached/10.F12254000800: 33.1875 /mnt/1wire/uncached/10.F12754000800: 33.1875 /mnt/1wire/uncached/10.F43054000800: 33.125 /mnt/1wire/uncached/10.F84C54000800: 33.125 /mnt/1wire/uncached/10.F8866B000800: 33.25 /mnt/1wire/uncached/10.F93D54000800: 33.125 /mnt/1wire/uncached/10.FA1E54000800: 33.125 /mnt/1wire/uncached/10.FC2154000800: 33.125 /mnt/1wire/uncached/10.FD1D54000800: 33.125 cat: /mnt/1wire/uncached/12.15DF1F000000/temperature: No such file or directory /mnt/1wire/uncached/12.15DF1F000000: cat: /mnt/1wire/uncached/12.4AE41F000000/temperature: No such file or directory /mnt/1wire/uncached/12.4AE41F000000: cat: /mnt/1wire/uncached/12.F3EA1F000000/temperature: No such file or directory /mnt/1wire/uncached/12.F3EA1F000000: /mnt/1wire/uncached/22.018503000000: 33.1875 /mnt/1wire/uncached/28.EB6731000000: 33.3125 cat: /mnt/1wire/uncached/2C.8EF604000000/temperature: No such file or directory /mnt/1wire/uncached/2C.8EF604000000: cat: /mnt/1wire/uncached/89.852BC300705E/temperature: No such file or directory /mnt/1wire/uncached/89.852BC300705E: cat: /mnt/1wire/uncached/alarm/temperature: No such file or directory /mnt/1wire/uncached/alarm: /mnt/1wire/uncached/simultaneous: 0 ------------------------------------------------------- This SF.Net email is sponsored by the 'Do More With Dual!' webinar happening July 14 at 8am PDT/11am EDT. 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