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


Question

I'm using Python with -c to execute a one-liner loop, i.e.:

$ python -c "for r in range(10): print 'rob'"

This works fine. However, if I import a module before the for loop, I get a syntax error:

$ python -c "import sys; for r in range(10): print 'rob'"
  File "<string>", line 1
    import sys; for r in range(10): print 'rob'
              ^
SyntaxError: invalid syntax

Any idea how this can be fixed?

It's important to me to have this as a one-liner so that I can include it in a Makefile.

1
168
4/16/2019 9:36:43 PM

Accepted Answer

you could do

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

or w/out 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 / @Crast's answer

155
11/14/2018 9:43:53 PM

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

python - <<EOF
import sys
for r in range(3): print 'rob'
EOF

or

python - <<-EOF
    import sys
    for r in range(3): print 'rob'
EOF

in latter 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 manpage or here).


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