No output when run in a loop.

[tthomas7]

Redirecting stdin from a file works as expected but piping from another command returns immediately as if nothing was found.

while read -r line; do Ack "$line"; done < search_terms
finds the search terms listed in the file.

cat search_terms | while read -r line; do Ack "$line"; done;
returns immediately.

[petdance]

Why are you calling Ack instead of ack?

[tthomas7]

that's a good question. I didn't know there was a difference

[petdance]

Might be, might not be. Do you have some sort of Ack alias that aliases to ack or something? What OS are you on? Do you just have a case-insensitive filesystem?

[tthomas7]

I'm using OSX and zsh, it is case insensitive I believe. I just tried LS and that works and ack doesn't change the behavior.

[ghost]

@tthomas7 that's a good question. I didn't know there was a difference

On Linux and other Unixoid systems there is a difference between lowercase and uppercase command.

[petdance]

The Mac HFS+ filesystem is case-insensitive, by default I believe, so that explains that.

[hleeldc]

I think it has something to do with this line: https://github.com/petdance/ack2/blob/dev/Ack.pm#L47

$is_filter_mode = -p STDIN;

This evaluates to 1 (true) when STDIN is from a pipe. Because of this, ack expects data to search from STDIN.

[petdance]

So this is our old nemesis "figuring out if we're filtering or not".