Executing multi-line statements in the one-line command-line?

This style can be used in makefiles too (and in fact it is used quite often).

python - <<EOF
import random
for r in range(3): print(random.randint(1, 42))
EOF

Or with hard tabs:

python - <<-EOF
    import random
    for r in range(3): print(random.randint(1, 42))
EOF
# Important: Replace the indentation above w/ hard tabs.

In above case, leading TAB characters are removed too (and some structured outlook can be achieved).

Instead of EOF can stand any marker word not appearing in the here document at a beginning of a line (see also here documents in the bash man page or here).

You could do

echo -e "import sys\nfor r in range(10): print 'rob'" | python

Or without pipes:

python -c "exec(\"import sys\nfor r in range(10): print 'rob'\")"

Or

(echo "import sys" ; echo "for r in range(10): print 'rob'") | python

Or SilentGhost's answer or Crast's answer.