gistfile1.sh

#!/bin/bash
set -x

char=a

declare -i int
int=a

declare -p char int

gistfile10.sh

#!/bin/bash

fpath=/usr/local/bin/gistfile1.sh
echo "path              : ${fpath}"
echo "dirname           : ${fpath%/*}"

name=${fpath##*/}
echo "basename (w   ext): ${name}"
echo "basename (w/o ext): ${name%.*}"
echo "extension         : ${name##*.}"

gistfile11.sh-session

path              : /usr/local/bin/gistfile1.sh
dirname           : /usr/local/bin
basename (w   ext): gistfile1.sh
basename (w/o ext): gistfile1
extension         : sh

gistfile2.sh-session

+ char=a
+ declare -i int
+ int=a
+ declare -p char int
declare -- char="a"
declare -i int="0"

gistfile3.sh-session

$ echo $BASH
/bin/bash
$ echo $BASH_VERSION
4.3.11(1)-release
$ echo ${BASH}_VERSION
/bin/bash_VERSION
$ echo "$BASH"_VERSION
/bin/bash_VERSION
$ echo $BASH.VERSION
/bin/bash.VERSION

gistfile4.sh-session

$ VERSION=VERSION
$ echo $BASH_$VERSION
VERSION
$ echo $BASH-$VERSION
/bin/bash-VERSION

gistfile5.sh-session

$ declare -p BASH_VERSINFO
declare -ar BASH_VERSINFO='([0]="4" [1]="3" [2]="39" [3]="1" [4]="release" [5]="armv7l-unknown-linux-gnueabihf")'

gistfile6.sh

#!/bin/bash

declare -p BASH_VERSINFO

echo \${BASH_VERSINFO[0]}: ${BASH_VERSINFO[0]}
echo \${BASH_VERSINFO[1]}: ${BASH_VERSINFO[1]}
echo \${BASH_VERSINFO[2]}: ${BASH_VERSINFO[2]}
echo \${BASH_VERSINFO[3]}: ${BASH_VERSINFO[3]}
echo \${BASH_VERSINFO[4]}: ${BASH_VERSINFO[4]}
echo \${BASH_VERSINFO[5]}: ${BASH_VERSINFO[5]}

echo \$BASH_VERSINFO[0]: $BASH_VERSINFO[0]
echo \$BASH_VERSINFO[1]: $BASH_VERSINFO[1]
echo \$BASH_VERSINFO[2]: $BASH_VERSINFO[2]
echo \$BASH_VERSINFO[3]: $BASH_VERSINFO[3]
echo \$BASH_VERSINFO[4]: $BASH_VERSINFO[4]
echo \$BASH_VERSINFO[5]: $BASH_VERSINFO[5]

gistfile7.sh-session

declare -ar BASH_VERSINFO='([0]="4" [1]="3" [2]="39" [3]="1" [4]="release" [5]="armv7l-unknown-linux-gnueabihf")'
${BASH_VERSINFO[0]}: 4
${BASH_VERSINFO[1]}: 3
${BASH_VERSINFO[2]}: 39
${BASH_VERSINFO[3]}: 1
${BASH_VERSINFO[4]}: release
${BASH_VERSINFO[5]}: armv7l-unknown-linux-gnueabihf
$BASH_VERSINFO[0]: 4[0]
$BASH_VERSINFO[1]: 4[1]
$BASH_VERSINFO[2]: 4[2]
$BASH_VERSINFO[3]: 4[3]
$BASH_VERSINFO[4]: 4[4]
$BASH_VERSINFO[5]: 4[5]

gistfile8.sh

#!/bin/bash

declare -p BASH_VERSINFO

j=${#BASH_VERSINFO[@]}

for ((i = 0; i < j; i++))
do
    echo \${BASH_VERSINFO[${i}]}: ${BASH_VERSINFO[i]}
done

for ((i = 0; i < j; i++))
do
    echo \$BASH_VERSINFO[i]: $BASH_VERSINFO[i]
done

gistfile9.sh-session

declare -ar BASH_VERSINFO='([0]="4" [1]="3" [2]="39" [3]="1" [4]="release" [5]="armv7l-unknown-linux-gnueabihf")'
${BASH_VERSINFO[0]}: 4
${BASH_VERSINFO[1]}: 3
${BASH_VERSINFO[2]}: 39
${BASH_VERSINFO[3]}: 1
${BASH_VERSINFO[4]}: release
${BASH_VERSINFO[5]}: armv7l-unknown-linux-gnueabihf
$BASH_VERSINFO[i]: 4[i]
$BASH_VERSINFO[i]: 4[i]
$BASH_VERSINFO[i]: 4[i]
$BASH_VERSINFO[i]: 4[i]
$BASH_VERSINFO[i]: 4[i]
$BASH_VERSINFO[i]: 4[i]

imgtojpg.sh

#!/bin/sh
set -e

CONVERT=`which convert`

for f
do
    test -f "${f}" || continue

    case ${f} in
    *.?|*.??|*.???|*.????)
        of=${f%.*}.jpg
    ;;
    *)
        of=${f}.jpg
    ;;
    esac

    test ! -e "${of}" || continue

    (
        set -x
        ${CONVERT} "${f}" "${of}"
    )
done