Re: [TUHS] Binary log files

John Cowan wrote in &lt;CAD2gp_SXHQSauT_VibXPvP6PWrFULiMFYkvfs5=YxjHYbHGPwg(a)mail.gmail.com&gt;: |As long ago as the 7th Edition, several binary log files were maintained: |the file generated by acct(2) (one record per process) and the utmp and |wtmp files (one record per login). Both of these are defined by structs in |.h files, so they are definitely not portable (int sizes, endianism, etc.) And how did you handle it? On a very current GNU/Linux system these files grow indefinetely, and sometimes you find several megabytes that track years of data, and yourself writing (nonetheless quickshot) truncation code like #?0|kent:~# less bin/truncate-wutmp.sh #!/bin/sh - #@ /root/bin/truncate-wutmp.sh trap 'rm -f /tmp/.doit-${$}.*' EXIT cat >/tmp/.doit-${$}.c <<'_EOT' #include <utmp.h> #include <stdio.h> int main(){ printf("%lu\n", sizeof(struct utmp)); return 0; } _EOT cc -o /tmp/.doit-${$}.exe /tmp/.doit-${$}.c || exit 1 i=$(/tmp/.doit-${$}.exe) echo "struct utmp is ${i} bytes" cd /var/log s=$(stat -c '%s' wtmp) [ ${?} -eq 0 ] || exit 2 echo "wtmp size is ${s} bytes" ix=$((s / i)) echo "... that makes ${ix} utmp entries" [ ${ix} -gt 42 ] || exit 3 ix=$((ix - 42)) dd if=wtmp of=wtmp.new bs=${i} skip=${ix} || exit 4 mv wmtp.new wtmp chmod 0644 wtmp # s-sh-mode --steffen | |Der Kragenbaer, The moon bear, |der holt sich munter he cheerfully and one by one |einen nach dem anderen runter wa.ks himself off |(By Robert Gernhardt)