[Solved] How to bind a shell command to a hotkey? (raspi2png)

hermit

@Clyde perfect :) tested with both snes and amiga :) Thanks a lot :)

thank you all :)

Clyde

Okay, I finally got around working on this. Here's my tested solution:

Install triggerhappy:

sudo apt install triggerhappy

Change its service configuration file using sed to run it as user pi for writing permissions in that user's $HOME directory (optional, but needed for the example below):

sudo sed -i -e 's/nobody/pi/' /etc/systemd/system/multi-user.target.wants/triggerhappy.service

Use thd to find the code of the key you want to connect a shell command to:

thd --dump /dev/input/*      # exit with CTRL+C

Put the code and the desired shell command into a fittingly named file in the directory /etc/triggerhappy/triggers.d/
Example: Running the raspi2png command from above on the press of "Print Screen", using the config file /etc/triggerhappy/triggers.d/raspi2png.conf:

KEY_SYSRQ 1 raspi2png --pngname "/home/pi/$(ps a | grep RetroPie/roms | awk -F "/" 'NR==1 { print $NF }' | sed 's/\.[^.]*$//g; s/\\//g')"-$(date +%Y.%m.%d-%H.%M.%S).png

KEY_SYSRQ is the code for the "Print Screen" key on most standard keyboards.
"1" = pressing the key, "2" = holding the key down, "0" = releasing the key
The rest is the command or script to run in this event. You may have to add the path to your raspi2png if it's not in your shell's search path like /home/pi/bin is for example.
Optional: Put the command in a shell script and run the script from the .conf file. See @roslofs post below. This may be advisable for multiple commands or if you change them from time to time, sparing you the reloading of the demon (see #4).

Reload the service to apply the changes:

sudo systemctl daemon-reload                 # reload the changes in triggerhappy.service
sudo systemctl restart triggerhappy.service  # reload the changes in /etc/triggerhappy/triggers.d/

Now, in the above example, pressing "Print Screen" should save a screenshot named after the currently running ROM file in the directory /home/pi/.

Comments, test results, corrections, and enhancements are welcome. :)

edit: You can check the status and any error messages of the triggerhappy daemon with the command sudo systemctl status triggerhappy.service.
edit 2: Changed the raspi2png command to @mitu's optimised version.
edit 3: Added @mitu's correction and @roslofs script variant.

Clyde

Credits go to @mitu, @Zigurana, @Djon, and @Headrush69 for their groundwork in https://retropie.org.uk/forum/topic/2377/control-volume-through-retroarch-with-keyboard and https://retropie.org.uk/forum/topic/18133/triggerhappy-daemon-thd-doesn-t-work-on-my-pi-running-retropie-help.

mitu

@Clyde Hey, you got it working - great stuff !

Now, the suggestions :) :

You can probably replace the long line of

`ps a|grep RetroPie/roms/|head -1|sed -e 's/ /_/g'|awk '{ print $NF }'|sed 's/\\\//g'`

with something like

ps a | grep RetroPie/roms | head -1 | awk -F "/" '{ print $NF }'

This will get you the last path segment (which can be a file or folder) from the line containing the ROM path.

EDIT: this will also preserve whitespaces in the filename, so it's not a drop-in replacement for the original command.

You're assuming the ROM is a .zip, but that not might be the case. Can't think of a simple and elegant way of dealing with this but I have an idea.

Clyde

@mitu I already played around with awk -F but I got no good results.

raspi2png --pngname /home/pi/$(basename -s .zip `ps a | grep RetroPie/roms/ | head -1 | awk -F "/" '{ print $NF }'`).png

will save a file called 7th\, whereas my command will save 7th_Saga,_The_(USA).png.

edit: I gave up on preserving the whitespaces. :)
edit 2: Have to leave for the gym now. I'm curious about your idea about the rom's filename extension.

mitu

If you don't quote your argument, spaces will surely be a problem. Anyway, here it is what I got so far.

raspi2png --pngname "$(ps a | grep RetroPie/roms | awk -F "/" 'NR==1 { print $NF }' | sed 's/\.[^.]*$//g')"-$(date +%Y.%m.%d-%H.%M.%S).png

This should work with spaces, regardless of extension, and adds a timestamp at the end. If you'd like to keep the date format the way RetroArch does it, you can use:

raspi2png --pngname "$(ps a | grep RetroPie/roms | awk -F "/" 'NR==1 { print $NF }' | sed 's/\.[^.]*$//g')"-$(date +%y%m%d-%H%M%S).png

Now, the RetroArch reference got me thinking, so I checked and you can tell RA to take a screenshot with the Network control interface - https://docs.libretro.com/tech/network-control-interface/. Assuming you got RA configured to start this interface (I don't think it's enabled by default, I just have it for the power off/reset buttons), the command to take a screenshot can be just

echo -n "SCREENSHOT" | nc -u -w1 127.0.0.1 55355

and a screenshot would be saved in ~/.config/retroarch/screenshots (a.k.a. /opt/retropie/configs/all/retroarch/screenshots or \\retropie\configs\all\retroarch\screenshots). You'll need netcat installed to provide the nc command.

Clyde

@mitu said in How to bind a shell command to a hotkey? (raspi2png):

If you don't quote your argument, spaces will surely be a problem. Anyway, here it is what I got so far.
raspi2png --pngname "$(ps a | grep RetroPie/roms | awk -F "/" 'NR==1 { print $NF }' | sed 's/\.[^.]*$//g')"-$(date +%Y.%m.%d-%H.%M.%S).png

This still won't get rid of the backslashes, e.g. creating Super\ Mario\ Bros.\ $2P\ Hack$-2019.02.23-18.10.44.png. But it does work with the .nes extension of this rom, thanks!

raspi2png --pngname "$(ps a | grep RetroPie/roms | awk -F "/" 'NR==1 { print $NF }' | sed 's/\.[^.]*$//g')"-$(date +%y%m%d-%H%M%S).png

Same here: Super\ Mario\ Bros.\ $2P\ Hack$-190223-181049.png

echo -n "SCREENSHOT" | nc -u -w1 127.0.0.1 55355

Works like a charm, thanks again for this alternative!

mitu

Yes, the dreaded \, forgot about them - I was testing with an emulator started. This can be fixed taking the sed command from your initial line:

raspi2png --pngname "$(ps a | grep RetroPie/roms | awk -F "/" 'NR==1 { print $NF }' | sed 's/\.[^.]*$//g; s#\\##g')"-$(date +%Y.%m.%d-%H.%M.%S).png

E.T.\ The\ Extra-Terrestrial\ $1982$\ $Atari$\ $PAL$\ \[\!\]-2019.02.23-17.20.15.png becomes E.T. The Extra-Terrestrial (1982) (Atari) (PAL) [!]-2019.02.23-17.25.43.png

Clyde

@mitu To answer in German: Wunderbar! 😄

Clyde

@mitu said in How to bind a shell command to a hotkey? (raspi2png):

aspi2png --pngname "$(ps a | grep RetroPie/roms | awk -F "/" 'NR==1 { print $NF }' | sed 's/\.[^.]*$//g; s#\\##g')"-$(date +%Y.%m.%d-%H.%M.%S).png

You might want to change that to raspi2png with an "r". 😉

edit: Aaaand … I saw your post changing while I was waiting for this post to appear. 😆

mitu

@Clyde I already did :). Anyway, I think you should add a reference to your solution post to your 1st post, so people can find it without reading to the whole topic.
Now the challenge is to find the equivalent of raspi2png for other platforms (Odroid, Pc).

Clyde

@mitu Did you read my mind? I just did that. 😱 😄

edit: Er … sorry, I didn't do that, but added a reference of your raspi2png solution to my first one. Adding the reference that you meant now. 😳

Clyde

@mitu Done, along with "[Solved]" in the title and my How-To updated with your raspi2png line.

I love communities like this for such constructive synergy. 😊

roslof

Love this thread, but I may need a smidgen more help to get this to work.

I followed Clyde's guide to the letter, but after pressing the defined key, entering sudo systemctl status triggerhappy.server yields:

Feb 23 19:01:19 retropie thd[2523]: Executing trigger action: raspi2png --pngname "/home/pi/$(ps a | grep RetroPie/roms | awk -F "/" 'NR==1 { print $NF }' | sed 's/.[^.]*$//g; s <---abruptly ends
Feb 23 19:01:19 retropie thd[2523]: sh: 1: Syntax error: Unterminated quoted string

Looks like it's cutting off the command line... No idea why. It looks fine in the config file. Actually, I just noticed that the line is being cut after EXACTLY 128 characters... So I wager I'm experiencing some character line limit that y'all are not.
Edit: It turned out the character limit was a red herring and not the cause.

FWIW, if I copy the same information from Step 4 into bash (removing KEY_SYSRQ 1) it works fine, and raspi2png takes the shot and the output file is named correctly. So the syntax as provided by Clyde (via Mitu) is definitely correct.

I'm only having trouble w/triggerhappy truncating the line from the config file in triggers.d.

Any advice?

mitu

@roslof If you post the contents of the /etc/triggerhappy/triggers.d/raspi2png.conf we may be able to spot any errors.

roslof

@mitu You bet, but it really is the same as step 4 above, and it definitely works at a bash prompt:

KEY_SYSRQ 1 raspi2png --pngname "/home/pi/$(ps a | grep RetroPie/roms | awk -F "/" 'NR==1 { print $NF }' | sed 's/\.[^.]*$//g; s#\\##g')"-$(date +%Y.%m.%d-%H.%M.%S).png

Syntax-wise, this is good. It just gets cropped during parsing after the 128th character.

I did, however, figure out a work-around. I just created a separate script/.sh to run raspi2png w/all the parameters. Then I just called the script from raspi2png.conf ;-)

My work-around:

Newly added /etc/triggerhappy/triggers.d/run-raspi2png.sh ensure executable perm flag is set

raspi2png --pngname "/home/pi/$(ps a | grep RetroPie/roms | awk -F "/" 'NR==1 { print $NF }' | sed 's/\.[^.]*$//g; s#\\##g')"-$(date +%Y.%m.%d-%H.%M.%S).png

Revised /etc/triggerhappy/triggers.d/raspi2png.conf

KEY_SYSRQ 1 /etc/triggerhappy/triggers.d/run-raspi2png.sh

Edit Note: Previously posted a line that used nohup, which was non-essential. For the curious, it was: KEY_SYSRQ 1 nohup /etc/triggerhappy/triggers.d/run-raspi2png.sh 0<&- &>/dev/null &

I have to say, the command-line arguments you and Clyde created are super-creative. I never would have imagined a screen capture with proper naming, and a solution for ANY emulator, including non-Retroarch. Great work, guys!

roslof

removed post based on insights from mitu

mitu

@roslof That's not necessary on Raspbian (and RetroPie) since the pi user is already a member of the video group and has access to /dev/vchiq. This kind of advice (make the /dev/whatever writable to anyone) it's just encouraging bad practice - don't do it, instead make sure your user is in the correct group.

roslof

@mitu Helpful. I'll edit the post. Unclear why I was in this state.

Clyde

@roslof Thanks for reporting this and for the workaround. I'll admit that I didn't test the last version of the string (note to myself: always test things before putting them online, even slight alterations of existing things).

It can't be the length (alone), though. I tested the command echo "...1.........2.........3..." and so on to test a string limit for command in the raspi2png.conf, but it worked well up to the 140 characters that I tested.

This is the output of sudo systemctl status triggerhappy.service with the last version of @mitu's string:

Feb 24 09:11:54 raspi thd[1458]: Executing trigger action: raspi2png --pngname "$(ps a | grep RetroPie/roms | awk -F "/" 'NR==1 { print $NF }' | sed 's/\.[^.]*$//g; s
Feb 24 09:11:54 raspi thd[1458]: sh: 1: Syntax error: Unterminated quoted string

Thanks for the compliments, I want to add @Lolonois who provided the very first part of the command string.

@mitu My knowledge about bash fu is very limited. Do you have any idea what can cause this?