Aggregating coding blogs
Andy Balaam from Andy Balaam's Blog
I was recording some podcast audio tonight and wanted to be able to press a single key when I reached a significant moment, so I could add the times to the show notes.
I couldn’t find anything that already did this, so I wrote a tiny bash script. I ran this script pressed Enter whenever I wanted a time recorded:
T=0
echo
while sleep 1; do
echo -n -e "\e[1A"
echo $(($T / 60))m $(($T % 60))s
T=$(($T + 1))
done
Andy Balaam from Andy Balaam's Blog
I love Bash tab completion, and I want it for the command I am writing, so it can automatically complete parts of the command line when I run my program.
Here is the script (install-bash-completion) I wrote to set it up (no need to be root – it installs in ~/.local):
#!/bin/bash
set -u
set -e
DIR=${BASH_COMPLETION_USER_DIR:-${XDG_DATA_HOME:-$HOME/.local/share}/bash-completion}/completions
mkdir -p ${DIR}
cp _myprogram ${DIR}
The actual completion script (_myprogram) it installs looks like this:
_myprogram_commands()
{
local cur prev opts
COMPREPLY=()
cur="${COMP_WORDS[COMP_CWORD]}"
prev="${COMP_WORDS[COMP_CWORD-1]}"
opts=$(bash -c "./myprogram --commands")
COMPREPLY=( $(compgen -W "${opts}" -- ${cur}) )
return 0
}
complete -F _myprogram_commands ./myprogram
To install it, run:
./install-bash-completion
Then log out and log in again.
Now when you type ./myprogram and press TAB a couple of times, you should see the possible completions listed.
The completion script must be named to match the program name, with a leading underscore.
If I wanted it to work when it was installed in my PATH, I would need to change ./myprogram to just myprogram in 2 places.
Notice the line opts=$(bash -c "./myprogram --commands") – it actually runs my program to get the list of completions. This means my program needs to accept a --commands option which prints the valid commands. Alternatively, I could have hard-coded it by replacing that line with just:
opts="cmd1 cmd2 --help --etc"
More info:
Andy Balaam from Andy Balaam's Blog
Here’s a little script I wrote to avoid copy-pasting the ffmpeg command from superuser every time I needed it.
It converts a video to a GIF file by pre-calculating a good palette, then using that palette.
Usage:
./to_gif input.mp4 output.gif
The file to_gif (which should be executable):
#!/bin/bash
set -e
set -u
# Credit: https://superuser.com/questions/556029/how-do-i-convert-a-video-to-gif-using-ffmpeg-with-reasonable-quality
INPUT="$1"
OUTPUT="$2"
PALETTE=$(tempfile --suffix=.png)
ffmpeg -y -i "${INPUT}" -vf palettegen "${PALETTE}"
ffmpeg -y -i "${INPUT}" -i "${PALETTE}" \
-filter_complex "fps=15,paletteuse" "${OUTPUT}"
rm -f "${PALETTE}"
Note: you might want to modify the number after fps= to adjust how fast the video plays.
Andy Balaam from Andy Balaam's Blog
I’ve been getting very excited about keybase.io recently, not least because it offers secure conversation, and you can have bots.
I wrote a quick bot to simulate Arnold Schwarzenegger which I thought I’d share to demonstrate how easy it is. It is based on the keybase command line tool (which comes with the desktop client as standard) and jq, the brilliant command-line JSON manipulator.
For this to work, you need to have the keybase command installed and working, and you need jq.
Here’s the bot:
#!/bin/bash
CHANNEL=mychannel
keybase chat api-listen | while read L; do
{
OUT=$(jq --raw-output 'select(.type == "chat")|select(.msg.content.text.body|startswith("!arnie "))| .msg.content.text.body | "*" + ltrimstr("!arnie ") + "*"' <<< "$L")
if [ "${OUT}" != "" ]; then
{
keybase chat send "${CHANNEL}" "${OUT}"
}; fi
}; done
and here's it working:
andy> !arnie Do eet do eet now!!! andy> Do eet do eet now!!!
Note: here the bot is pretending to be me. To do this nicely, you will want a different account for the bot, but you get the idea.
Obviously, I am now working on a comprehensive bot framework in Rust. Watch this space.