Quick command line math

expr 512 \* 7
expr will give you a quick way to do basic math from the CLI. Make sure you escape things like * and leave a space between operators and digits.
Sample Output
expr 44 + 99 + 128
271

4
By: chuckr
2009-09-23 19:11:38

What Others Think

Doesn't do decimals. Try this Perl command. perl -le 'print 51.2 * 2'
billbose · 473 weeks ago
bc does floating point, large powers and trig functions too bc 3584 bc -l 73.14285714285714285714 bc 9223372036854775808
Escher · 472 weeks and 6 days ago
the comment above came out wrong bc <<< 512*7 3584 bc -l <<< 512/7 73.14285714285714285714 bc <<< 512^7 9223372036854775808
Escher · 472 weeks and 6 days ago
if you don't care about decimals then try echo $((512*7)) you don't need to care about spaces nor escaping anything
edo · 472 weeks and 6 days ago
All good solutions too. But the original wins for fewest number of keystrokes :-) Also, the bc example above seems wrong. echo "512*7" | bc will work.
chuckr · 472 weeks and 6 days ago
the bc examples use bash 'here string' operator, it won't work in other shells, but in bash it's the fewest keystrokes, and more versatile.
Escher · 472 weeks and 6 days ago
bc <<< 512*7 is 12 keystrokes expr 512 \* 7 is 13 keystrokes
Escher · 472 weeks and 6 days ago
and in fact, it could just be bc<<<512*7 which is 10 keystrokes.
Escher · 472 weeks and 6 days ago
OK. I wasn't using bash when trying the '
chuckr · 472 weeks and 6 days ago
OK. I wasn't using bash when trying the 'here string' solution so I didn't count its keystrokes. Good solution, if using bash.
chuckr · 472 weeks and 6 days ago

What do you think?

Any thoughts on this command? Does it work on your machine? Can you do the same thing with only 14 characters?

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