pattern matching operators PART 1

commandline session

$cat pm.sh
#!/bin/bash

filename=${1##*/}

echo $filename
$sh pm.sh /bin/bash
bash
$vim pm.sh
$cat pm.sh
#!/bin/bash

filename=${1}

echo $filename
$sh pm.sh /bin/bash
/bin/bash
$vim pm.sh
$cat pm.sh
#!/bin/bash

filename=${#}

echo $filename
$sh pm.sh /bin/bash
1
$vim pm.sh
$cat pm.sh
#!/bin/bash

filename=${##}

echo $filename
$sh pm.sh /bin/bash
1
$vim pm.sh
$cat pm.sh
#!/bin/bash

filename=${*}

echo $filename
$sh pm.sh /bin/bash
/bin/bash
$vim pm.sh
$cat pm.sh
#!/bin/bash

filename=${/}

echo $filename
$sh pm.sh /bin/bash
pm.sh: 3: pm.sh: Bad substitution
$