Some handy one-liner shell scripts.
Note: if you're on Windows, all of these tools are available 
as part of the free Cygwin tookkit (www.cygwin.com).
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# Delete all jobs matching the pattern "job=DELETEME*".
p4 jobs -e "job=DELETEME*" | cut -d " " -f 1 | xargs -n 1 p4 job -d

# List all changelists that contributed via integration to target change CHANGE.
p4 files @CHANGE,@CHANGE | sed s/#.*/@CHANGE/ | p4 -x - filelog -m1 | grep "^\.\.\. \.\.\." | grep -v "into" | grep -v "ignored by" | sed "s/.*\/\//\/\//" | p4 -x - changes

# List all files opened on any client owned by USER, without using p4 opened -a.
p4 -Ztag clients | grep -B3 "... Owner USER" | grep "... client" | cut -d ' ' -f 3 | xargs -n1 p4 opened -a -C

# Delete all empty submitted changelists.
p4 changes -s submitted | cut -d " " -f 2 | xargs -n1 p4 change -d -f