gawk: noeffect.awk:2: warning: statement may have no effect
gawk: noeffect.awk:3: warning: statement may have no effect
gawk: noeffect.awk:5: warning: statement may have no effect
gawk: noeffect.awk:2: warning: reference to uninitialized variable `s'
gawk: noeffect.awk:3: warning: reference to uninitialized variable `s'