mjhjmtu

There are some contrast output between awk arithmetic and expr.

Example

expr 11111111111111111111 / 22

gives

505050505050505050

but with awk:

echo '11111111111111111111' | awk 'q=$1/22;;print q'

gives

505050505050505024

Can somebody explain?

Presumably your awk works with floating point values, like GNU awk seems to do:

$ gawk 'BEGIN a = 11111111111111111111; print a, a/22; '
11111111111111110656 505050505050505024

It can't store 11111111111111111111 accurately, and it can't store the remainder accurately either (11111111111111111111 / 22 is 505050505050505029.81...).

Your expr seems to have a wider numeric range. Mine doesn't (the one from GNU coreutils 8.26):

$ expr 11111111111111111111 / 22
expr: 11111111111111111111: Numerical result out of range

As @steeldriver comments, current versions of GNU awk also have the capability to use the GNU MPFR library for high-precision arithmetic. For example, quad-precision floats are enough to give an accurate answer for this division:

$ gawk -M -v PREC="quad" -v OFMT="%.6f" 
 'BEGIN a = 11111111111111111111; print a, a/22; '
11111111111111111111 505050505050505050.500000

Other that that, bc or Python can be used for arbitrarily large numbers.