I was trying to write a Bash script to clean up the old checkpoints in
my Jupyter notebooks directories, which have been accumulating for
some years. The first version looked like this:

BASEDIR=~/Documents/Jupyter\ Notebooks/
CHECKPOINTSDIR=.ipynb_checkpoints
NRDAYS=30 # delete everything older than this

collect_checkpoints_dirs()
{
local -n arr="$1"
arr=()
coproc collector { find "$BASEDIR" -type d -name "$CHECKPOINTSDIR" -print0; }
# must ensure while-loop runs in this process
while read -u ${collector[0]} -rd '' line; do
arr[${#arr[*]}]="$line"
done
wait $collector_PID
} # collect_checkpoints_dirs

collect_checkpoints_dirs dirs

echo "${dirs[@]}"
for dir in "${dirs[@]}"; do
find "$dir" -maxdepth 1 -type f -mtime +${NRDAYS} -print0 | xargs -0 rm -fv
done

but it didn’t work. I figured out that the BASEDIR and CHECKPOINTSDIR variables were not being properly expanded inside the coproc command.
If I substitute those values literally

coproc collector { find ~/Documents/Jupyter\ Notebooks/ -type d -name .ipynb_checkpoints -print0; }

then it works.

How would I pass variables into that coproc command?

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In article <10893ja$1dihv$[email protected]>,
Lawrence DOliveiro <[email protected]d> wrote:

I was trying to write a Bash script to clean up the old checkpoints in
my Jupyter notebooks directories, which have been accumulating for
some years. The first version looked like this:

...

but it didnt work. I figured out that the BASEDIR and CHECKPOINTSDIR >variables were not being properly expanded inside the coproc command.
If I substitute those values literally

coproc collector { find ~/Documents/Jupyter\ Notebooks/ -type d -name
.ipynb_checkpoints -print0; }

then it works.

How would I pass variables into that coproc command?

First, I think you should switch to using "mapfile" instead of "coproc/read". "mapfile" is extremely good for this sort of thing and I tend to use it in
all my scripts. In fact, the main script that I've been developing for
almost 5 years now, uses "coproc" at its core because when I first started, "coproc" looked interesting - and I hadn't really gotten used to "mapfile"
at that point. Not likely to go back and change it at this point, but,
looking back on it, I think if I had it to do all over again, I wouldn't
use "coproc" at all.

Try:

mapfile -t < <(find "$BASEDIR" -type d -name "$CHECKPOINTSDIR")

Note: This will fail if you have directory names with newlines in them, but then again, if you have directory names with newlines, you're in pretty bad straits already...

Second, my first reaction to your problem was that you need to export the variables (if you think it through, that kinda makes sense), but I just did
the following little test and it did the right thing:

$ foo=bar
$ coproc { echo "$foo"; }; read -u$COPROC; echo $REPLY
bar
$

So, I don't know...

--
What can you do with this besides printing sarcastic and obscene messages to the
screens of lusers at login or logout?

From the man page for "strfile(1)".

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In article <[email protected]>,
Christian Weisgerber <[email protected]> wrote:

On 2025-08-22, Kenny McCormack <[email protected]> wrote:

Try:

mapfile -t < <(find "$BASEDIR" -type d -name "$CHECKPOINTSDIR")

Note: This will fail if you have directory names with newlines in them,

mapfile -d '' -t < <(find ... -print0)

As I said, if you have directory names with newlines in them, then you have more serious problems than I can help you with.

--
https://en.wiktionary.org/wiki/res_ipsa_loquitur

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On 2025-08-22, Kenny McCormack <[email protected]> wrote:

Try:

mapfile -t < <(find "$BASEDIR" -type d -name "$CHECKPOINTSDIR")

Note: This will fail if you have directory names with newlines in them,

mapfile -d '' -t < <(find ... -print0)

--
Christian "naddy" Weisgerber [email protected]

--- SoupGate-Win32 v1.05
* Origin: fsxNet Usenet Gateway (21:1/5)

In article <10893ja$1dihv$[email protected]>,
Lawrence DOliveiro <[email protected]d> wrote:

I was trying to write a Bash script to clean up the old checkpoints in
my Jupyter notebooks directories, which have been accumulating for
some years. The first version looked like this:

I wonder if OP is still reading this thread. I'm curious how it all worked out. In particular, I'd like to know if there *is* any problem passing (un-exported) variables into coprocs.

--
Meatball Ron wants to replace the phrase "climate change" with the phrase "energy dominance" in policy discussions.

Yeah, like that makes a lot of sense...

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