In /usr/bin/sas_disk_blink line 38:
    s|-set) shift ; let seconds="$1" ;;
                    ^---------------^ SC2219: Instead of 'let expr', prefer (( expr )) .


In /usr/bin/sas_disk_blink line 72:
    let res=$?
    ^--------^ SC2219: Instead of 'let expr', prefer (( expr )) .


In /usr/bin/sas_disk_blink line 73:
    if [ $res -ne 0 ]
         ^--^ SC2086: Double quote to prevent globbing and word splitting.

Did you mean: 
    if [ "$res" -ne 0 ]


In /usr/bin/sas_disk_blink line 75:
        exit $res
             ^--^ SC2086: Double quote to prevent globbing and word splitting.

Did you mean: 
        exit "$res"


In /usr/bin/sas_disk_blink line 79:
        let start=0
        ^---------^ SC2219: Instead of 'let expr', prefer (( expr )) .


In /usr/bin/sas_disk_blink line 81:
        let start=1
        ^---------^ SC2219: Instead of 'let expr', prefer (( expr )) .


In /usr/bin/sas_disk_blink line 85:
        if [ $start -eq 0 ]
             ^----^ SC2086: Double quote to prevent globbing and word splitting.

Did you mean: 
        if [ "$start" -eq 0 ]


In /usr/bin/sas_disk_blink line 88:
            let res=$?
            ^--------^ SC2219: Instead of 'let expr', prefer (( expr )) .


In /usr/bin/sas_disk_blink line 89:
            if [ $res -ne 0 ]
                 ^--^ SC2086: Double quote to prevent globbing and word splitting.

Did you mean: 
            if [ "$res" -ne 0 ]


In /usr/bin/sas_disk_blink line 91:
                exit $res
                     ^--^ SC2086: Double quote to prevent globbing and word splitting.

Did you mean: 
                exit "$res"


In /usr/bin/sas_disk_blink line 98:
            let res=$?
            ^--------^ SC2219: Instead of 'let expr', prefer (( expr )) .


In /usr/bin/sas_disk_blink line 99:
            if [ $res -ne 0 ]
                 ^--^ SC2086: Double quote to prevent globbing and word splitting.

Did you mean: 
            if [ "$res" -ne 0 ]


In /usr/bin/sas_disk_blink line 101:
                exit $res
                     ^--^ SC2086: Double quote to prevent globbing and word splitting.

Did you mean: 
                exit "$res"

For more information:
  https://www.shellcheck.net/wiki/SC2086 -- Double quote to prevent globbing ...
  https://www.shellcheck.net/wiki/SC2219 -- Instead of 'let expr', prefer (( ...