ref: 6b6b9a236d773c704daaf7f7b5b090111e28ac87
dir: /sys/src/cmd/upas/binscripts/tfmt.rc/
#!/bin/rc # anti-topposting defense # sed '/^[ ]*>[ ]*>[ ]*>/q' awk ' { if(l[i] ~ /^[ ]*>[ ]*>[ ]*>/) q = 1 if(q == 0) l[i = NR] = $0; } END{ for(; i > 1; i--) if(l[i] !~ /^([ ]*>)*[ ]*$/) break; for(; i > 1; i--) if(l[i] !~ /^[ ]*>[ ]*>/) break; for(; i > 1; i--) if(l[i] !~ /^([ ]*>)*[ ]*$/) break; for(j = 1; j <= i; j++) print l[j] }' |dd -conv block >[2=]