how do I search for multiple patterns?

[xfzv]

I'm doing some tests with the following:

❯ fd --min-depth 2 --max-depth 2 -g "*-9999*" "/var/db/pkg" | cut -d "/" -f 5-6 | sed 's/-9999*//g'
app-portage/eix
x11-wm/awesome

• test.txt:

x11-wm/awesome:0
app-portage/eix:0

• test.sh:

#!/usr/bin/env bash

echo "grep output"
grep "$(fd --min-depth 2 --max-depth 2 -g "*-9999*" "/var/db/pkg" | cut -d "/" -f 5-6 | sed 's/-9999*//g')" test.txt
grep -c "$(fd --min-depth 2 --max-depth 2 -g "*-9999*" "/var/db/pkg" | cut -d "/" -f 5-6 | sed 's/-9999*//g')" test.txt
echo ""

echo "rg output"
rg -U "$(fd --min-depth 2 --max-depth 2 -g "*-9999*" "/var/db/pkg" | cut -d "/" -f 5-6 | sed 's/-9999*//g')" test.txt
rg -U --count "$(fd --min-depth 2 --max-depth 2 -g "*-9999*" "/var/db/pkg" | cut -d "/" -f 5-6 | sed 's/-9999*//g')" test.txt

Basically, I'd like to count how many times the output of the fd command (app-portage/eix and x11-wm/awesome) appear in test.txt.

When running test.sh, grep finds the two matches but rg gives me no output:

❯ ./test.sh
grep output
x11-wm/awesome
app-portage/eix
2

rg output

Maybe I'm missing an option? is this because rg considers the output of the fd command as a single pattern instead of two distinct patterns?

[BurntSushi]

Please provide a command or sequence of commands that I can run on my machine that reproduces the problem. Your commands given depend on the directory contents of /var/db/pkg of your specific machine.

Note also that you've enabled -U/--multiline for ripgrep. There is no equivalent for grep. So you aren't using identical commands.

[xfzv]

Please provide a command or sequence of commands that I can run on my machine that reproduces the problem. Your commands given depend on the directory contents of /var/db/pkg of your specific machine.

I can reproduce on an Arch Linux VM with the following:

$ su -
# mkdir -p /var/db/pkg/app-portage/eix-99999999
# mkdir -p /var/db/pkg/x11-wm/awesome-9999


# fd --min-depth 2 --max-depth 2 -g "*-9999*" "/var/db/pkg" | cut -d "/" -f 5-6 | sed 's/-9999*//g'
app-portage/eix
x11-wm/awesome

# echo "app-portage/eix:0" > test.txt
# echo "x11-wm/awesome:0" >> test.txt

# grep "$(fd --min-depth 2 --max-depth 2 -g "*-9999*" "/var/db/pkg" | cut -d "/" -f 5-6 | sed 's/-9999*//g')" test.txt
app-portage/eix:0
x11-wm/awesome:0

# grep -c "$(fd --min-depth 2 --max-depth 2 -g "*-9999*" "/var/db/pkg" | cut -d "/" -f 5-6 | sed 's/-9999*//g')" test.txt
2

# rg "$(fd --min-depth 2 --max-depth 2 -g "*-9999*" "/var/db/pkg" | cut -d "/" -f 5-6 | sed 's/-9999*//g')" test.txt
the literal '"\n"' is not allowed in a regex

Consider enabling multiline mode with the --multiline flag (or -U for short).
When multiline mode is enabled, new line characters can be matched.

# rg -U "$(fd --min-depth 2 --max-depth 2 -g "*-9999*" "/var/db/pkg" | cut -d "/" -f 5-6 | sed 's/-9999*//g')" test.txt
(no output)

# rg -U --count "$(fd --min-depth 2 --max-depth 2 -g "*-9999*" "/var/db/pkg" | cut -d "/" -f 5-6 | sed 's/-9999*//g')" test.txt
(no output)

Note also that you've enabled -U/--multiline for ripgrep. There is no equivalent for grep. So you aren't using identical commands.

As you can see in the sequence of commands above, I added -U as suggested by ripgrep.

[BurntSushi]

Well there's your problem. The pattern you've provided to ripgrep contains a \n. It looks like GNU grep treats that \n as delimiting multiple patterns. ripgrep has different behavior. Instead it tells you that you can't search for \n in a pattern unless multi-line mode is enabled. So by enabling multi-line mode, you're now searching for the entire pattern including the \n. Just use the -f/--file flag instead:

$ rg -f <(fd --min-depth 2 --max-depth 2 -g "*-9999*" "./var/db/pkg" | cut -d "/" -f 5-6 | sed 's/-9999*//g') test.txt
1:app-portage/eix:0
2:x11-wm/awesome:0

It also works with grep.

[xfzv]

Thank you for the detailed explanation.

rg -f <(fd --min-depth 2 --max-depth 2 -g "*-9999*" "/var/db/pkg" | cut -d "/" -f 5-6 | sed 's/-9999*//g') test.txt

works fine indeed.