Here's a few clarifications:
- shutdown (with no params or shutdown 0) is no longer a dependable way to reboot into single user mode. It was pretty good at versions 8 and 9 and even early 10.xx, but recently it has been unreliable, leaving mounted directories like /opt and /var and multi-user processes running. An interrupted boot process is the only reliable way today.
- make_recovery has been replaced with make_tape_recovery (which is based on make_net_recovery) and should be replaced with the latest version on all your systems. NOTE: the options have changed, so the recommended command should be:
# make_tape_recovery -AIv -a /dev/rmt/some_tape
- ioscan has a wide variety of reallty useful options. The most important is -k (the warp speed option--try it). Here are some really useful examples:
# ioscan -knf
# ioscan -knfC disk
# ioscan -kfC tape
# ioscan -kC processor
# ioscan -kfnH 8/10/5
# ioscan -knfH 12
- lpstat -t works well except when there are a lot of remote printers that must be polled. If any of the servers are down, there is a LONG delay to timout. To see just the current list of printers, use lpstat -v
- grep (-E -F or egrep and fgrep) egrep handles extended regular expressions but is quite slow. Since most uses of egrep (or grep -E) use the multiple search option, try this as an alternative...these two produce equivalent results but grep -F is much faster:
# grep -Ei "err|warn|panic|crit" syslog.log
# grep -Fi -e err -e warn -e panic -e crit syslog.log
So here's my favorite to prevent core dumps: in /etc/profile, put this line:
ulimit -Sc 0
It allows a knowledgeable user to change the value but if left alone, no core files will be produced.
Bill Hassell, sysadmin
