$1 represents the first argument to your script, so your for loop is only ever iterating over that.

Use $@ to represent all arguments:

for i in "$@"; do
    doi "$i"
done

Additionally, it is important to understand that Papers/*.pdf is not a regular expression, it's filename expansion with globbing.

It's important to understand that Papers/*.pdf is not a regular expression, it's a wildcard pattern that causes bash to perform filename expansion, or globbing.

$1 represents the first argument to your script, so your for loop is only ever iterating over that one argument.

Use $@ to represent all arguments:

for i in "$@"; do
    doi "$i"
done

$1 means the first argument, so your for loop is only ever iterating over that.

Use $@ to represent all arguments:

for i in "$@"; do
    doi "$i"
done

Additionally, it is important to understand that Papers/*.pdf is not a regular expression, it's filename expansion with globbing.

$1 represents the first argument to your script, so your for loop is only ever iterating over that.

Use $@ to represent all arguments:

for i in "$@"; do
    doi "$i"
done

Additionally, it is important to understand that Papers/*.pdf is not a regular expression, it's filename expansion with globbing.