A script to get a random file

Question

Dear developers,

I have an issue with my script switching from Android 9 to 10 (devices from a Umidigi S3 Pro to a Umidigi F2).

I have installed Bosybox App on the first and Busybox Magisk module on the latter.

Now the script does not work because the command:

list=(`busybox find "$dirs" -type f -name *.$ext`)

returns an empty array.

This is the complete script:

#!/system/bin/sh

echo

if test "$1" = ""; then


  echo "Randomfile script by Uranya <@uranya7x> v1.4 01.01.2021"


  echo "Usage:"


  echo "sh randomfile.sh <sourcedir> <extension> <destdir>"


  exit 1

fi

dirs=$1

ext=$2

dird=$3'/'

dest=$dird'random'

delim1=""

delim2=""

last='last.txt'

# create filename's array

IFS=$'\n'



list=(`busybox find "$dirs" -type f -name *.$ext`)



# count number of files

num=${
#list[@]
}


# generate random number in range 1-NUM

let "ran=(${
RANDOM
}
 % ${
num
}
)+ 1"

echo Random from $num files is $ran

sour=${
list[ran]
}


sourn=${
sour#$dirs
}


sourn=${
sourn:1:${
#sourn
}

}


date=$(date +"%Y.%m.%d %H:%M")

day=$(date +"%d")

hour=$(date +"%H")

minute=$(date +"%M")

message='---------------------------------------\n'$date' - '$num' >>> '$ran'\n'$delim1$sourn$delim2

if ([ "$day" = "01" ] && [[ "$minute" < "29" ]]) || [ ! -f $dird$last ]; then


 echo >$dird$last $message

else


 sed -i '1i'$message $dird$last

fi

echo $delim1$sourn$delim2

# rename the old file

cp $dest.$ext $dest'_back.'$ext

# copy the file

cat "$sour" >$dest.$ext

echo File copied as $delim1$dest.$ext$delim2

Can you please help me to understand why this happens, and how to fix it?
Thank you very much for your attention!

— Giuseppe Uranya Di Terlizzi | Sources

Answer

Dear friends,

after a couple of hours debugging the script, finally, I have found the mistake!
The line to be used is:
list=( find "$dirs" -type f -name "*.$ext" )

it is a very subtle difference: the space after and before the parenthesis!
(even, the word busybox is useless)

Oddly in the Busybox app (I have had on my S3 Pro) the spaces are not mandatory, whilst in the Busybox Magisk module those spaces ARE mandatory!

I'm using this script for almost 8 years to have an every day different music for my wake up.

I'm using Tasker to call it just before my alarm get off, so the same file contains every day, a different song.

I have done a change also in the array index that did not began by 0

So, here it is the right script:

#!/system/bin/sh

echo

if test "$1" = ""; then


 echo "Randomfile script by Uranya <@uranya7x> v1.5 (26.03.2021)"


 echo "Usage:"


 echo "sh randomfile.sh <sourcedir> <extension> <destdir>"


 exit 1

fi

dirs=$1

ext=$2

dird=$3'/'

dest=$dird'random'

delim1=""

delim2=""

last='last.txt'

# create filename's array

IFS=$'\n'

list=( `find "$dirs" -type f -name "*.$ext"` )

# count number of files

num=${
#list[@]
}


# generate random number in range 1-NUM

let "ran=(${
RANDOM
}
 % ${
num
}
)+ 1"

echo Random from $num files is $ran

sour=${
list[$ran-1]
}


sourn=${
sour#$dirs
}


sourn=${
sourn:1:${
#sourn
}

}


date=$(date +"%Y.%m.%d %H:%M")

day=$(date +"%d")

hour=$(date +"%H")

minute=$(date +"%M")

message='---------------------------------------\n'$date' - '$num' >>> '$ran'\n'$delim1$sourn$delim2

if ([ "$day" = "01" ] && [[ "$minute" < "29" ]]) || [ ! -f $dird$last ]; then


 echo >$dird$last $message

else


 sed -i '1i'$message $dird$last

fi

echo $delim1$sourn$delim2

# rename the old file

cp $dest.$ext $dest'_back.'$ext

# copy the file

cat "$sour" >$dest.$ext

echo File copied as $delim1$dest.$ext

I hope it will be useful to someone else that loves to be waked up by music.

Peace everywhere!

— Giuseppe Uranya Di Terlizzi | Sources

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