The first XTI call in a process evaluates the XTITRACE environment variable and, if necessary, enables the XTI trace. After the trace is enabled, the temporary XTIFpid trace file (pid specifies the process number) is opened in the desired directory (-f dir option, see the following page), if it is not already open. The trace data is written into this file.
If the XTIFpid cannot accept any further data, the subsequent trace data is written into the XTISpid file. This file has the same function as the XTIFpid file. Once the XTISpid is full, XTIFpid is cleaned up and the new trace data is then written into it. The trace mechanism can switch back and forth between the XTIFpid and XTISpid files a number of times if necessary. With each file change, the process should save the data in the temporary file that was just written, into a permanent file. This prevents the logged trace information from being overwritten and allows it to be output at a later time with the xtitrace program.
The rw------- (0600) access rights are granted for the XTIFpid and XTISpid trace files and they can be viewed under the user ID of the process. Memory is assigned dynamically for buffering the trace files. This memory, and the XTIFpid and XTISpid files, remain assigned for the duration of the process.
The options specified for XTITRACE control the trace mechanism:
The s and S options define the scope of information to be logged.
The r option controls the cyclic overwriting of the XTIFpid and XTISpid files.
The f option controls the memory for the XTIFpid and XTISpid files.
You set the XTITRACE environment variable parameters with the following statements:
XTITRACE="-option [ -r wrap][ -f dir]";export XTITRACE; |
-option
option defines the trace type. A value must be entered for option when a trace is enabled.
You can enter the following two values for option:
s
Logs the XTI call function names and their parameters and return values. If errors occur, the values of t_errno and errno are logged and the error position errpos.
S
Logs all information which is also logged if s is specified. If parameters occur which are passed as pointers, the values of the objects addressed by the pointers are also logged.
Die Angabe S ist der Angabe s vorzuziehen.
S should be specified in preference to s.
-r wrap
You input a decimal number for wrap.
wrap defines that the trace file is changed after wrap * BUFSIZ bytes: after each wrap * BUFSIZ logged bytes, the trace mechanism switches over from the XTIFpid file to the XTISpid file and viceversa. The data in the file that is switched to is thereby overwritten in each case. The BUFSIZ constant is defined in <stdio.h>.
Default value for wrap: 512
-f dir
You use dir to specify the directory into which the XTIFpid and XTISpid trace files are written.
Default value for dir: /usr/tmp