Re: how to debug this strange load problem

[frank wang]

Hi, Przemek,

 

Your conclusion is correct. For some reason, octave treats the file as an empty file.

 

The version of linux I am using is:

Linux-132w 2.6.16.13-4-default.

 

Suse 10.1

 

Thanks

 

Frank

 

On 8/29/06, Przemek Klosowski <address@hidden> wrote:

I compared what happens on my system when I try to read Frank's file
containing the string "103\n104\n105" (three numbers on three lines,
with no terminating newline) with Frank's strace results:


-------------my system-----------------------        ------------Frank---------------------------

open("/tmp/d", O_RDONLY)                = 3           open(" test2.txt", O_RDONLY|O_LARGEFILE) = 3
close(3)                                = 0           close(3)                                = 0
futex(0x3b8b31fc60, FUTEX_WAKE, 2147483647) = 0
brk(0x19f3000)                          = 0x19f3000
open("/tmp/d", O_RDONLY)                = 3
fstat(3, {st_mode=S_IFREG|0664, st_size=11, ...}) = 0
lseek(3, 0, SEEK_SET)                   = 0
read(3, "103\n104\n", 8)                = 8
close(3)                                = 0
open("/tmp/d", O_RDONLY)                = 3           open("test2.txt", O_RDONLY|O_LARGEFILE) = 3
read(3, "103\n104\n105", 8191)          = 11          read(3, "103\n104\n105", 8191)          = 11
lseek(3, 0, SEEK_SET)                   = 0           _llseek(3, 0, [0], SEEK_SET)            = 0
read(3, "103\n104\n105", 8191)          = 11          read(3, "103\n104\n105", 8191)          = 11
read(3, "", 8191)                       = 0           read(3, "", 8191)                       = 0
lseek(3, 0, SEEK_SET)                   = 0           _llseek(3, 0, [0], SEEK_SET)            = 0
lseek(3, 124, SEEK_SET)                 = 124         _llseek(3, 124, [124], SEEK_SET)        = 0
read(3, "", 8191)                       = 0           read(3, "", 8191)                       = 0
lseek(3, 0, SEEK_SET)                   = 0           _llseek(3, 0, [0], SEEK_SET)            = 0
read(3, "103\n104\n105", 8191)          = 11          read(3, "103\n104\n105", 8191)          = 11
read(3, "", 8191)                       = 0           read(3, "", 8191)                       = 0
close(3)                                = 0           close(3)                                = 0
open("/tmp/d", O_RDONLY)                = 3
read(3, "103\n104\n105", 8191)          = 11
close(3)                                = 0
open("/tmp/d", O_RDONLY)                = 3
lseek(3, 0, SEEK_CUR)                   = 0
read(3, "103\n104\n105", 8191)          = 11
read(3, "", 8191)                       = 0
lseek(3, 0, SEEK_SET)                   = 0
read(3, "103\n104\n105", 8191)          = 11
read(3, "", 8191)                       = 0
close(3)                                = 0
read(0, "", 4096)                       = 0

Clearly, the I/O libraries are different, but the behavior seems to be similar, except for the
third seek (lseek(3, 124, SEEK_SET)) which for some weird reason seeks to position 124 in this
11-byte file. On Frank's system it seems to result in going to offset 0 but the subsequent read
returns an empty string (compare with the next two lines, where it asks to go to zero, returns
zero and reads the whole file again.

Frank---what is your Linux flavor/version  again?

Also, Frank---if the 'load test2.txt' read worked, it would have created an octave variable test2:

octave:1> load test2.txt
octave:2> test2
test2 =

103
104
105

Did you check that particular variable name?