Search for substring matches in a file bash - regex

Question

The premise is to store a database file of colon separated values representing items.
var1:var2:var3:var4
I need to sort through this file and extract the lines where any of the values match a search string.
For example
Search for "Help"
Hey:There:You:Friends
I:Kinda:Need:Help (this line would be extracted)
I'm using a function to pass in the search string, and then passing the found lines to another function to format the output. However I can't seem to be able to get the format right when passing. Here is sample code i've tried of different ways that I've found on this site, but they don't seem to be working for me
#Option 1, it doesn't ever find matches
function retrieveMatch {
if [ -n "$1" ]; then
while read line; do
if [[ *"$1"* =~ "$line" ]]; then
formatPrint "$line"
fi
done
fi
}
#Option 2, it gets all the matches, but then passes the value in a
#format different than a file? At least it seems to...
function retrieveMatch {
if [ -n "$1" ]; then
formatPrint `cat database.txt | grep "$1"`
fi
}
function formatPrint {
list="database.txt" #default file for printing all info
if [ -n "$1" ]; then
list="$1"
fi
IFS=':'
while read var1 var2 var3 var4; do
echo "$var1"
echo "$var2"
echo "$var3"
echo "$var4"
done < "$list"
}
I can't seem to get the first one to find any matches
The second options gets the right values, but when I try to formatPrint, it throws an error saying that the list of values passed in are not a directory.

Answer 1

Honestly, I'd replace the whole thing with
function retrieveMatch {
grep "$1" | tr ':' '\n'
}
To be called as
retrieveMatch Help < filename
...like the original function (Option 1) appeared to be designed. To do more complicated things with matching lines, have a look at awk:
# in the awk script, the fields in the line will be $1, $2 etc.
awk -v pattern="$1" -F : '$0 ~ pattern { for(i = 1; i < NF; ++i) print $i }'
See this link. Awk is made to process exactly this sort of data, so if you plan to do complex things with it, it is definitely worth a look.
Answering the question more directly, there are two/three problems in your code. One is, as was pointed out in the comments to the question, that the line
if [[ *"$1"* =~ "$line" ]]; then
Will try to use "$line" as a regular expression to find a match in *"$1"*, assuming that *"$1"* does not become more than one token after pathname expansion because the * are not quoted. Assuming that the * are supposed to match anything the way they would in glob expressions (but not in regular expressions), this could be replaced with
if [[ "$line" =~ "$1" ]]; then
because =~ will report a match if the regex matches any part of the string.
The second problem is that you're divided on whether you want "$list" in formatPrint to be a file or a line. You say in retrieveMatch that it should be a line:
formatPrint "$line"
But you set it to a filename default in formatPrint:
list="database.txt" #default file for printing all info
You'll have to decide on one. If you decide that formatPrint should format lines, then the third problem is that the redirection in
while read var1 var2 var3 var4; do
echo "$var1"
echo "$var2"
echo "$var3"
echo "$var4"
done < "$list"
tries to use "$list" as a filename. This could be fixed by replacing the last line with
done <<< "$list" # using a here-string (bash-specific)
Or
done <<EOF
$list
EOF
(note: in the latter case, do not indent the code; it's a here-document that's taken verbatim). And, of course, read will only split four fields the way you wrote it.

Answer 2

I feel I must be missing something, but..
cat > foo.txt
Hey:There:You:Friends I:Kinda:Need:Help
Foo:Bar
[Give control-D]
grep -i help foo.txt
Hey:There:You:Friends I:Kinda:Need:Help
Does it fit the bill?
EDIT: To expand a little further on this thought..
cat > foo.bsh
#!/bin/bash
hits="$(grep -i help foo.txt)"
while read -r line; do
echo "${line}"
done <<< "$hits"
[Give control-D]