33.4. Tests and Comparisons: Alternatives

For tests, the [[ ]] construct may be more appropriate than [ ]. Likewise, arithmetic comparisons might benefit from the (( )) construct.

1 a=8 2  3 # All of the comparisons below are equivalent. 4 test "$a" -lt 16 && echo "yes, $a < 16" # "and list" 5 /bin/test "$a" -lt 16 && echo "yes, $a < 16" 6 [ "$a" -lt 16 ] && echo "yes, $a < 16" 7 [[ $a -lt 16 ]] && echo "yes, $a < 16" # Quoting variables within 8 (( a < 16 )) && echo "yes, $a < 16" # [[ ]] and (( )) not necessary. 9  10 city="New York" 11 # Again, all of the comparisons below are equivalent. 12 test "$city" \< Paris && echo "Yes, Paris is greater than $city" 13  # Greater ASCII order. 14 /bin/test "$city" \< Paris && echo "Yes, Paris is greater than $city" 15 [ "$city" \< Paris ] && echo "Yes, Paris is greater than $city" 16 [[ $city < Paris ]] && echo "Yes, Paris is greater than $city" 17  # Need not quote $city. 18  19 # Thank you, S.C.