在终端中找到作品但在bash脚本中失败

Question

So I'm writing a bash script that counts the number of files in a directory and outputs a number. The function takes a directory argument as well as an optional file-type extension argument.

I am using the following lines to set the dir variable to the directory and ext variable to a regular expression that will represent all the file types to count.

dir=$1
[[ $# -eq 2 ]] && ext="*.$2" || ext="*"

The problem I am encountering occurs when I attempt to run the following line:

echo $(find $dir -maxdepth 1 -type f -name $ext | wc -l)

Running the script from the terminal works when I provide the second file-type argument but fails when I don't.

harrison@Luminous:~$ bash Documents/howmany.sh Documents/ sh
3
harrison@Luminous:~$ bash Documents/howmany.sh Documents/
find: paths must precede expression: Desktop
Usage: find [-H] [-L] [-P] [-Olevel] [-D help|tree|search|stat|rates|opt|exec] [path...] [expression]
0

I have searched for this error and I know it's an issue with the shell expanding my wildcard as explained here . I've tried experimenting with single quotes, double quotes, and backslashes to escape the asterisk but nothing seems to work. What's particularly interesting is that when I try running this directly through the terminal, it works perfectly fine.

harrison@Luminous:~$ echo $(find Documents/ -maxdepth 1 -type f -name "*" | wc -l)
6

Answer 1

Simplified:

dir=${1:-.}           #if $1 not set use .
name=${2+*.$2}        #if $2 is set use *.$2 for name
name=${name:-*}       #if name still isnt set, use *

find "$dir" -name "$name" -print   #use quotes

or

name=${2+*.$2}        #if $2 is set use *.$2 for name
find "${1:-.}" -name "${name:-*}" -print   #use quotes

also, as @John Kugelman says, you could use:

 name=${2+*.$2}
 find "${1:-.}" ${name:+-name "$name"} -print

find . -name "*" -print find . -name "*" -print is the same as find . -print find . -print , so if $name isn't set, there's no need to specify -name "*" .

Answer 2

Try this:

dir="$1"
[[ $# -eq 2 ]] && ext='*.$2' || ext='*'

If that doesn't work, you can just switch to an if statement, where you use the -name pattern in a branch and you don't in the other.

A couple more points:

• Those are not regular expressions , but rather shell patterns .
• echo $(command) is just equivalent to command .