Recursive Arch Linux Shell Script To Get Dependencies - bash

Question

I wrote a shell script to print out to a file all of the dependencies from a specified package. Obviously it's not working (or else I wouldn't be here lol). I'm new to shell scriping / bash programming. I am running on Arch Linux and have searched the web to get me to where I'm at. But now I get a bunch of errors from a "empty string package name". It starts off good, then it's an endless loop of doom. My current code is this:
#!/bin/bash
echo -n "Enter a package: "
read p
echo "Searching through package...$p"
get_dependencies() {
# Make sure we get the package too...
pacman -Sp "$1" >> myPackages.list
# Get dependency list from current package and output to tmp file
pacman -Si "$1" | awk -F'[:<=>' '/^Depends/ {print $2}' | xargs -n1 | sort -u > depList.list
# Read from that output file and store in array
listArray=()
while read -r input ; do
listArray+=("$input")
done < "depList.list"
# Get the number of dependencies
numList=${#listArray[#]}
echo "$numList dependencies from $1"
echo "Delving deeper.."
# Loop through each depend and get all those dependencies
for i in "${listArray[#]}" ; do
get_dependencies "$i"
done
}
# Get dependcies of package that user typed
get_dependencies "$p"
# Finished
echo "Done!"

Answer 1

To avoid cyclic dependencies, you can keep track of what packages you've visited and which you have yet to visit in seperate files. Comparing those files before descending into the dependencies will hopefully keep your script out of trouble.
deps() {
pacman -Si "$1" |
awk -F'[:<=>]' '/^Depends/ {print $2}' |
xargs -n1 |
sort -u |
grep -v None
}
alldeps() {
# needed files, potentially cached for later
unseen_f=unseen.$1.txt
seen_f=seen.$1.txt
deps_f=deps.$1.txt
# start of with the root packaage
echo $1 > $unseen_f
# while we still have unseen packages, find depends
while [ $(sed /^$/d $unseen_f |wc -l ) -gt 0 ]; do
# read in all unseen, and get their deps
for d in $(cat $unseen_f); do
echo $d >> $seen_f
deps $d >> $deps_f
done
# those in deps but not in seen to go unseen
# we'll finish when unseen is empty: nothing in deps we haven't seen
comm -23 <(sort -u $deps_f) <(sort -u $seen_f) > $unseen_f
done
cat $seen_f
#sort -u $seen_f $deps_f
# rm $seen_f $deps_f $unseen_f
}
alldeps xterm