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3.4 Compile-Time Macro Reference | 153
At startup, the value in the $j defined macro (?§21.9.59 on page 830) is added to the class w
(?§22.6.16 on page 876). If sendmail is compiled withXDEBUG, it periodically checks to
make sure that $j is still listed in class w. If $j should vanish, sendmail will log the following
at LOG_ALERT, dump its state (?§14.1.5 on page 510), and abort(3):
daemon process doesn't have $j in $=w; see syslog
WithXDEBUG defined, sendmail periodically checks to see whether its standard I/O file
descriptors have gotten clobbered. If so, it logs the following and tries to recover by
connecting it to /dev/null:
where: fd which not open
Here, where will reflect the internal subroutine name and arguments that led to the check,
and which will be the bad file descriptor number.
If you are running a precompiled sendmail binary, you can use the -d0.1 debugging
command-line switch (?§15.7.1 on page 542) to determine whether XDEBUG support is
included (if it appears in the list, support is included).
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154
Chapter 4 CHAPTER 4
Maintain Security with sendmail
When the administrator is not careful, the misuse or misconfiguration of sendmail can
lead to an insecure and possibly compromised system.
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