Linux

pstree -pl

ps -ejH

ps auxf

Solaris

ptree

HPUX

ptree

pstree — for only one user

Linux

pstree -ap $USER

Solaris

ptree -a $USER

ptree -a $USER | perl -nae 'printf "%-8s %s", (getpwuid((stat "/proc/$F[0]")[4]))[0], $_'

AIX

ps -fT1 | less -p $USER

ps -fT1 | perl -nle 'BEGIN{$user=shift} s/(?=.{'$COLUMNS'}).*//; $cur = /^ *$user/; print if $cur; print "\n" if $last && !$cur; $last=$cur' $USER