changing default paht in TMUX terminal text graphic

2020.01.26

Tmux: easily change the default path for new windows

Tmux is a wonderful terminal multiplexer, a little newer and a little more fun than the GNU Screen that you may be used to. This article outlines a drop-in solution for changing the default path for new Tmux windows from within a Tmux session.

In Tmux the directory where you begin your session becomes the default path for new windows. Sometimes you night want to change this while still inside the session.

Before version 1.9

Versions of Tmux prior to 1.9 offered the ability to change this via setting a simple session option:

tmux set-option default-path /some/new/path

After 1.9

But after 1.9, although you can pass any path to the new-window command, the only remaining straightforward way to just change the default path for new windows in a session overall is to detach and reattach the session in the new directory.

That’s too much of an interruption for me!

Some people juggle environment variables and send them to new-window to get around this, but I wanted less fuss in my tmux.conf so I wrote an external script to do all the work.

Essentially, the move is to make a new detached session and reattach the original session in the new directory inside of that session. Yes, this is awkward, but it’s not my fault! 🤷

Solution

This script!

Use like:

tmux-chdir /some/new/directory

#!/usr/bin/env bash
# [Christopher Peterson](https://chrispeterson.info)

# Details of this script's function are in the help output

# Establish random session name
chars='123456789ABCDEFGHIJKLMNOPQRSTUVWXYZ'
tmp_session=$(
  for i in {1..8}; do
    echo -n "${chars:RANDOM%${#chars}:1}"
  done
)

######
# Args
######
read -r -d '' helpoutput <<EOF
  Usage:
    ${0} [ARGS]

      Changes the default path for new windows from *within* a Tmux session.
      (Works with versions both before 1.9 and after)

  Positional arguments:
    [ARGS]
        A new default path in which Tmux should open new windows.

  Example
      ${0} /new/default/path

  Dependencies:
    * Bash
    * Tmux
    * bc
    * grep
EOF

fail_help() {
  echo "${helpoutput}"
  exit 1
}

if [ $# -ne 1 ]; then
  fail_help
fi

######
# Deps
######
command -v bash >/dev/null || fail_help
command -v bc >/dev/null || fail_help
command -v grep >/dev/null || fail_help
command -v tmux >/dev/null || fail_help
command -v wc >/dev/null || fail_help

######
# Traps
######
trap early_exit SIGINT
early_exit() {
  tmux kill-session -t "${tmp_session}"
  exit $?
}

######
# Main
######
newdir="${1}"
if ! [ -d "${newdir}" ]; then
  exit 1
fi

session_client_count () {
  sess="${1}"
  count=$(tmux list-clients -t "${sess}" | wc -l)
  echo "${count}"
}

if [ -z "${TMUX}" ]; then
  exit 1
fi
vers=$(tmux -V | grep -Po '[0-9\.]*')

curr_session=$(tmux display -p '#S')

# This is dumb but stay with me - Tmux doesn't use semver
if (( $(echo "${vers} < 1.9" | bc -l) )); then
  tmux set-option default-path "${newdir}"
else
  # In order to change the default working directory in Tmux >=1.9 from
  # *within* the same session, we'll need to jump through some hoops.
  # So! Make a new session and inside that session, attach the *first* session
  # in a manner that alters the default path. Then, kill the second session and
  # you're back where you started, but with a new working dir 👍
  tmux new-session -d -t "${tmp_session}"
  tmux send-keys -t "${tmp_session}" 'unset TMUX' Enter
  client_count=$(session_client_count "${curr_session}")
  tmux send-keys -t "${tmp_session}" "tmux attach-session -t \"${curr_session}\" -c \"${newdir}\"" Enter
  start_count="${client_count}"
  while (( client_count <= start_count )); do
    client_count=$(session_client_count "${curr_session}")
  done
  tmux kill-session -t "${tmp_session}"
fi

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#!/usr/bin/env bash

# [Christopher Peterson](https://chrispeterson.info)

# Details of this script's function are in the help output

# Establish random session name

chars='123456789ABCDEFGHIJKLMNOPQRSTUVWXYZ'

tmp_session=$(

for i in {1..8}; do

echo -n "${chars:RANDOM%${#chars}:1}"

done

)

######

# Args

######

read -r -d '' helpoutput <<EOF

Usage:

${0} [ARGS]

Changes the default path for new windows from *within* a Tmux session.

(Works with versions both before 1.9 and after)

Positional arguments:

[ARGS]

A new default path in which Tmux should open new windows.

Example

${0} /new/default/path

Dependencies:

* Bash

* Tmux

* bc

* grep

EOF

fail_help() {

echo "${helpoutput}"

exit 1

}

if [ $# -ne 1 ]; then

fail_help

fi

######

# Deps

######

command -v bash >/dev/null || fail_help

command -v bc >/dev/null || fail_help

command -v grep >/dev/null || fail_help

command -v tmux >/dev/null || fail_help

command -v wc >/dev/null || fail_help

######

# Traps

######

trap early_exit SIGINT

early_exit() {

tmux kill-session -t "${tmp_session}"

exit $?

}

######

# Main

######

newdir="${1}"

if ! [ -d "${newdir}" ]; then

exit 1

fi

session_client_count () {

sess="${1}"

count=$(tmux list-clients -t "${sess}" | wc -l)

echo "${count}"

}

if [ -z "${TMUX}" ]; then

exit 1

fi

vers=$(tmux -V | grep -Po '[0-9\.]*')

curr_session=$(tmux display -p '#S')

# This is dumb but stay with me - Tmux doesn't use semver

if (( $(echo "${vers} < 1.9" | bc -l) )); then

tmux set-option default-path "${newdir}"

else

# In order to change the default working directory in Tmux >=1.9 from

# *within* the same session, we'll need to jump through some hoops.

# So! Make a new session and inside that session, attach the *first* session

# in a manner that alters the default path. Then, kill the second session and

# you're back where you started, but with a new working dir 👍

tmux new-session -d -t "${tmp_session}"

tmux send-keys -t "${tmp_session}" 'unset TMUX' Enter

client_count=$(session_client_count "${curr_session}")

tmux send-keys -t "${tmp_session}" "tmux attach-session -t \"${curr_session}\" -c \"${newdir}\"" Enter

start_count="${client_count}"

while (( client_count <= start_count )); do

client_count=$(session_client_count "${curr_session}")

done

tmux kill-session -t "${tmp_session}"

fi

In case of any updates to this script, you can always check the live version in my dotfiles:

https://github.com/cspeterson/dotfiles/blob/master/.bin/tmux-chdir

UPDATE: From this reply in Reddit it seems there might be another way to do this. It doesn’t work for me, but here it is:

TMUX= TERM=ansi tmux attach -c /tmp \; detach >/dev/null

1	TMUX= TERM=ansi tmux attach -c /tmp \; detach >/dev/null

2018.09.24

Jekyll – use includes directly from plugins

Christopher Peterson Blog code, gem, jekyll, programming, Ruby

Jekyll is a popular static site generator that I’m using to develop the new Decipher SciFi site. It’s pretty sweet.

But!

Normally, Jekyll’s include tag can only search for files in the site’s single configured includes directory (and that of the theme plugin, if it using one). That means that if a plugin wants to provide you with a template/fragment via includes, the best it can do is ask you to copy it into your own repo manually. That sucks.

So I wrote jekyll-plugin-include: a gem-based Jekyll liquid tag plugin which allows includes directly from plugins’ _include directories, with optional ability to override with files present in site includes_dir (if they exist).

https://github.com/decipher-media/jekyll-plugin-include

This plugin then makes it easy to use includes that ship with a plugin directly from a plugin. And if a modified version of the file is provided in the site’s own includes directory, it can intelligently use that one instead!

And for plugin developers, this could provide a way to ship and use includes without leaning on the user to manage the unmodified files themselves.

ლ(╹◡╹ლ)

2018.09.07

Rclone remote path auto-completion on Linux (Google Drive)

Christopher Peterson Blog BASH, cli, code, Linux, terminal

UPDATE: My autocomplete script now ships with Rclone as of version 1.46. So you’re probably better off using that modified, maintained version than this old one here. This post will remain up as a reference. 🙂

—

I started playing with rclone in the interest of easily editing files from Google Drive with Vim. As it turns out, you can’t edit native Google Docs files in this manner, so that was a wash!

But a side benefit of this misadventure is this bash autocomplete script which I wrote to auto-complete remote paths for rclone with a Google Drive target. It probably works for others too, I haven’t tested them. 🙂

This implementation is in pure bash all except for the call to rclone itself to check against known remote targets. I appreciated An introduction to bash completion to get me started on the concepts, and the rest of what anyone needs is all in the bash manpage under complete.

Here in this post is the initial version I’m using. If you’re going to use it, check the current version of the file on my Github in case anything changes.

# rclone bash autocomplete
# Christopher Peterson [https://chrispeterson.info]
# This file provides a bash completion function for autocompleting remote
# Google Drive paths rclone
# It might well work with other cloud services supported by rclone, but I have
# not tested any others.

# Requirements:
#   rclone >= v1.40 # https://rclone.org/install/

# Installation:
#   Cat or copy this script into "${HOME}/.bash_completion", or
#   Copy this script into /etc/bash_completion.d/ for system-wide use
#
# Caveats:
#   Rclone itself also provides some bash autocompletion, though it does not
#   include remote paths. So this should override the other autocompletes, if
#   they are installed. In the future, I'll consider how to perhaps integrate
#   with them in the future.

_rclone_remote_ls() {
  local  foundremote opts remotename remotepath remotes rpath_cur rpath_start
  COMPREPLY=()

	# Since we're dealing with a colon in the remote path, we'll get the
	# current arg this way (colon is a stop character for readline)
	_get_comp_words_by_ref -n : cur

  # Check first that `cur` is an rclone remote in the form of
  # `remotename:words/`.  A slash (or multiple) may or may or may not be present.
  if ! [[ "${cur}" =~ ^[a-zA-Z0-9]*:.*/?.* ]]; then
    return
  fi

  # Split the path at the last slash
  remotename=${cur%:*}
  remotepath=${cur#*\:}

  remotes=($(rclone listremotes | sed 's/:$//g'))

  # Look for a remote drive matching the input
  foundremote=0
  for remote in "${remotes[@]}"; do
    if [ "${remotename}" = "${remote}" ]; then
      foundremote=1
      break
    fi
  done
  if ! [ "${foundremote}" -eq 1 ]; then
    return
  fi

  # If remote path has a slash, we can set up to look in a subdir.
  if [[  "${remotepath}" == */* ]]; then
    rpath_start=${remotepath%/*}
    rpath_cur=${remotepath##*/}
  else
    rpath_start=''
    rpath_cur="${remotepath}"
  fi

  # Create a final array containing matching file paths for bash autocomplete
  opts=()
  while IFS=  read -r line; do
    if [ -z "${rpath_start}" ]; then
      line=("${line}")
    else
      line=("${rpath_start}/${line}")
    fi
    echo "${line}" | grep -P "^${remotepath}" 2>&1 >/dev/null
    if [ "$?" -eq 0 ]; then
      opts+=("${line}")
    fi
  done < <(rclone lsf --max-depth 1 "${remotename}:${rpath_start}" 2>/dev/null)

  COMPREPLY=("${opts[@]}")
  return
}

complete -o filenames -F _rclone_remote_ls rclone

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# rclone bash autocomplete

# Christopher Peterson [https://chrispeterson.info]

# This file provides a bash completion function for autocompleting remote

# Google Drive paths rclone

# It might well work with other cloud services supported by rclone, but I have

# not tested any others.

# Requirements:

# rclone >= v1.40 # https://rclone.org/install/

# Installation:

# Cat or copy this script into "${HOME}/.bash_completion", or

# Copy this script into /etc/bash_completion.d/ for system-wide use

#

# Caveats:

# Rclone itself also provides some bash autocompletion, though it does not

# include remote paths. So this should override the other autocompletes, if

# they are installed. In the future, I'll consider how to perhaps integrate

# with them in the future.

_rclone_remote_ls() {

local foundremote opts remotename remotepath remotes rpath_cur rpath_start

COMPREPLY=()

# Since we're dealing with a colon in the remote path, we'll get the

# current arg this way (colon is a stop character for readline)

_get_comp_words_by_ref -n : cur

# Check first that `cur` is an rclone remote in the form of

# `remotename:words/`. A slash (or multiple) may or may or may not be present.

if ! [[ "${cur}" =~ ^[a-zA-Z0-9]*:.*/?.* ]]; then

return

fi

# Split the path at the last slash

remotename=${cur%:*}

remotepath=${cur#*\:}

remotes=($(rclone listremotes | sed 's/:$//g'))

# Look for a remote drive matching the input

foundremote=0

for remote in "${remotes[@]}"; do

if [ "${remotename}" = "${remote}" ]; then

foundremote=1

break

fi

done

if ! [ "${foundremote}" -eq 1 ]; then

return

fi

# If remote path has a slash, we can set up to look in a subdir.

if [[ "${remotepath}" == */* ]]; then

rpath_start=${remotepath%/*}

rpath_cur=${remotepath##*/}

else

rpath_start=''

rpath_cur="${remotepath}"

fi

# Create a final array containing matching file paths for bash autocomplete

opts=()

while IFS= read -r line; do

if [ -z "${rpath_start}" ]; then

line=("${line}")

else

line=("${rpath_start}/${line}")

fi

echo "${line}" | grep -P "^${remotepath}" 2>&1 >/dev/null

if [ "$?" -eq 0 ]; then

opts+=("${line}")

fi

done < <(rclone lsf --max-depth 1 "${remotename}:${rpath_start}" 2>/dev/null)

COMPREPLY=("${opts[@]}")

return

}

complete -o filenames -F _rclone_remote_ls rclone

2018.06.05

Splatmoji – easier quick pop-up emoji/emoticon input on Linux

Christopher Peterson Blog BASH, dmenu, emoji, emoticons, programming

I previously posted about an emoji-input method using iBus that required jumping through some hoops and ultimately wasn’t a very pretty UX.

But now I’ve rolled my own, and added japanese emoticons/kaomoji as a bonus! I’ve titled it Splatmoji, with respect to its wildcard nature for emotive text input.

Quick start:

# sudo apt-get install rofi xdotool xsel || sudo yum install rofi xdotool xsel
git clone https://github.com/cspeterson/splatmoji.git
cd splatmoji

# Call with default emoji and emoticon data files, copy result to clipboard
./splatmoji copy

# Call with default emoji and emoticon data files, type out result
./splatmoji type

# Call with a specific custom data file, copy result to clipboard
./splatmoji copy /path/to/data/file1 /path/to/data/file2

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# sudo apt-get install rofi xdotool xsel || sudo yum install rofi xdotool xsel

git clone https://github.com/cspeterson/splatmoji.git

cd splatmoji

# Call with default emoji and emoticon data files, copy result to clipboard

./splatmoji copy

# Call with default emoji and emoticon data files, type out result

./splatmoji type

# Call with a specific custom data file, copy result to clipboard

./splatmoji copy /path/to/data/file1 /path/to/data/file2

Some suggestions for customizing its configuration, binding it to a key combo in your window manager, using your own emoticon sets, and other bits are in the README.

＼(^▽^＠)ノ

2018.05.16

Query TMDB for movie and tv info on the commandline

Christopher Peterson Blog cli, code, Ruby

You know TMDB (The Movie DataBase)? It’s like IMDB, but without being awful.

tl;dr: I made a cli TMDB query tool in Ruby and here it is with documentation: https://github.com/decipher-media/tmdbget

As part of our podcast website migration from WordPress to Jekyll, I’m coding in a bunch of functionality that I’ve wanted for a while. The first one: a cli utility to fetch movie metadata into (semi-)structured data.

So here it is

https://github.com/decipher-media/tmdbget

Grab some API keys form TMDB and it’s easy-peasy to get some movie and tv metadata:

bundle exec tmdbget.rb --key [TMDB API KEY] 'the terminator'

1	bundle exec tmdbget.rb --key [TMDB API KEY] 'the terminator'

To get something like:

{
  "The Terminator": {
    "vote_count": 5259,
    "id": 218,
    "video": false,
    "vote_average": 7.4,
    "title": "The Terminator",
    "popularity": 21.31828,
    "poster_path": "/q8ffBuxQlYOHrvPniLgCbmKK4Lv.jpg",
    "original_language": "en",
    "original_title": "The Terminator",
    "genre_ids": [
      28,
      53,
      878
    ],
    "backdrop_path": "/6yFoLNQgFdVbA8TZMdfgVpszOla.jpg",
    "adult": false,
    "overview": "In the post-apocalyptic future, reigning tyrannical supercomputers teleport a cyborg assassin known as the \"Terminator\" back to 1984 to kill Sarah Connor, whose unborn son is destined to lead insurgents against 21st century mechanical hegemony. Meanwhile, the human-resistance movement dispatches a lone warrior to safeguard Sarah. Can he stop the virtually indestructible killing machine?",
    "release_date": "1984-10-26",
    "release_year": "1984"
  }
}

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{

"The Terminator": {

"vote_count": 5259,

"id": 218,

"video": false,

"vote_average": 7.4,

"title": "The Terminator",

"popularity": 21.31828,

"poster_path": "/q8ffBuxQlYOHrvPniLgCbmKK4Lv.jpg",

"original_language": "en",

"original_title": "The Terminator",

"genre_ids": [

28,

53,

878

],

"backdrop_path": "/6yFoLNQgFdVbA8TZMdfgVpszOla.jpg",

"adult": false,

"overview": "In the post-apocalyptic future, reigning tyrannical supercomputers teleport a cyborg assassin known as the \"Terminator\" back to 1984 to kill Sarah Connor, whose unborn son is destined to lead insurgents against 21st century mechanical hegemony. Meanwhile, the human-resistance movement dispatches a lone warrior to safeguard Sarah. Can he stop the virtually indestructible killing machine?",

"release_date": "1984-10-26",

"release_year": "1984"

}

Check the help output for full and up-to-date functionality details, including a flag for interactive mode for when you’re less than confident that you’ll get the right answer. 🤓

2018.03.19

Quick and easy unit conversions within Vim (vim-convert)

Christopher Peterson Blog vim

Header image bits: Vim logo from D0ktorz and SI Units from Dono

Editing some varieties of documents I noticed myself jumping into a browser or terminal often to do unit conversion. But no longer! Vim-convert is a plugin I made for Vim that allows easy unit conversion from a simple command.

The command

:Convert [[value]|[start unit]] {target unit}

1	:Convert [[value]\|[start unit]] {target unit}

Some usage examples

To convert in-place the currently visually-selected text which includes a
unit, e.g. 500g

:Convert {target unit}

1	:Convert {target unit}

To convert in-place the currently visually-selected text which does *not*
include a unit, e.g. 500, you’ll need to specify one:

:Convert {start unit} {target unit}

1	:Convert {start unit} {target unit}

To insert a unit conversion as a new value after the cursor, give both fields:

:Convert <value><start unit> <target unit>

1	:Convert <value><start unit> <target unit>

To cause an error because parsecs are a unit of distance:

:Convert 12parsecs hours

1	:Convert 12parsecs hours

This plugin will try to be mindful of whether the unit itself is desired when
replacing text. That is, if the selected text lacks a unit, the result will be
placed without one as well.

Installation instructions and other details in the README.

2018.03.05

A Linux ACPI brightness control script

Christopher Peterson Blog ACPI, BASH, i3wm, Linux

Brightness icon in featured image by Elegant Themes

When I started using i3 window manager, I knew I’d basically have to re-engineer a number of desktop environment features myself around the bare window manager. One of these features is easy brightness control on my laptop.

The Arch Wiki has a *great* and in-depth page on this as it can be a very complex matter with a bunch of different ways to manage it on different hardware. Here! But after that, and if the ACPI method works for you, here is the script I came up with to manage it on Ubuntu!

ACPI brightness controls

So if you see something listed like this then you probably have a backlight you can interact with

$ ls -l /sys/class/backlight/**
/sys/class/backlight/some_backlight/:
total 0
-r--r--r-- 1 root root actual_brightness
-rw-r--r-- 1 root root bl_power
-rw-r--r-- 1 root root brightness
lrwxrwxrwx 1 root root device -> ../../card0-someSCREEN
-r--r--r-- 1 root root max_brightness
drwxr-xr-x 2 root root power
lrwxrwxrwx 1 root root subsystem -> ../../../../../../../class/backlight
-r--r--r-- 1 root root type
-rw-r--r-- 1 root root uevent

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$ ls -l /sys/class/backlight/**

/sys/class/backlight/some_backlight/:

total 0

-r--r--r-- 1 root root actual_brightness

-rw-r--r-- 1 root root bl_power

-rw-r--r-- 1 root root brightness

lrwxrwxrwx 1 root root device -> ../../card0-someSCREEN

-r--r--r-- 1 root root max_brightness

drwxr-xr-x 2 root root power

lrwxrwxrwx 1 root root subsystem -> ../../../../../../../class/backlight

-r--r--r-- 1 root root type

-rw-r--r-- 1 root root uevent

The files we’re interested in are brightness and max_brightness. Writing a value into brightness will… change the brightness! But one must be root to do this.

$ echo /sys/class/backlight/some_backlight/max_brightness
900
# Maybe make it sane eh
$ sudo bash -c 'echo 500 > brightness'

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$ echo /sys/class/backlight/some_backlight/max_brightness

900

# Maybe make it sane eh

$ sudo bash -c 'echo 500 > brightness'

My script

So I made a script to do it! (Here is the current version of the script in my dotfiles, which may differ since the writing of this post)

#!/usr/bin/env bash
set -e

# Question: Under what circumstances could there be two backlight listings?
# If I had this, I would set it up to adjust each in turn maybe. But I don't.

# Usage
if [ "$#" -eq 0 ]; then
cat <<-EOF
Usage: $0 [command]
Increase or decrease screen brightness at hardware level by steps of 10% of
max, as determined by the values under /sys/class/backlight/**. Limit values
to the range of 0 to max_brightness.

up | Increase brightness by 10%
down | Decrease brightness by 10%
current | Report current brightness


This script needs root access - sudo is an option, but you may also consider
allowing your user to run the script without a password prompt e.g.:

# Append to /etc/sudoers
Cmnd_Alias BRIGHT_CMDS=/bin/path/bright up, /bin/path/bright down
username ALL=(root) NOPASSWD: BRIGHT_CMDS
EOF
exit 1
fi

# Gather information
backlight_dir='/sys/class/backlight'
device_dir=$(ls "${backlight_dir}" | head -n 1)
if [ -z "$device_dir" ]; then
echo 'No backlight hardware is listed in /sys/class/backlight! Quitting.'
exit 1
fi
device_dir="${backlight_dir}/${device_dir}"
brightness_file="${device_dir}/brightness"
curr_brightness=$(cat "${brightness_file}")
max_brightness=$(cat "${device_dir}/max_brightness")

if [ "$1" == 'current' ]; then
echo $( echo "(${curr_brightness} / ${max_brightness}) * 100" | bc -l) \
| cut -d'.' -f 1
else
direction=$1

# Calculate
step=$(( $max_brightness / 10 ))
if [ $direction == 'up' ]; then
new_brightness=$(( $curr_brightness + $step ))
elif [ $direction == 'down' ]; then
new_brightness=$(( $curr_brightness - $step ))
else
echo 'Argument $1 must be either "up" or "down". Quitting.'
exit 1
fi
# Limit range
if [ "$new_brightness" -gt "$max_brightness" ]; then
new_brightness="$max_brightness"
fi
if [ "$new_brightness" -lt 0 ]; then
new_brightness=0
fi

# "Do it" - the emperor
echo $new_brightness > "${brightness_file}"
fi

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#!/usr/bin/env bash

set -e

# Question: Under what circumstances could there be two backlight listings?

# If I had this, I would set it up to adjust each in turn maybe. But I don't.

# Usage

if [ "$#" -eq 0 ]; then

cat <<-EOF

Usage: $0 [command]

Increase or decrease screen brightness at hardware level by steps of 10% of

max, as determined by the values under /sys/class/backlight/**. Limit values

to the range of 0 to max_brightness.

up | Increase brightness by 10%

down | Decrease brightness by 10%

current | Report current brightness

This script needs root access - sudo is an option, but you may also consider

allowing your user to run the script without a password prompt e.g.:

# Append to /etc/sudoers

Cmnd_Alias BRIGHT_CMDS=/bin/path/bright up, /bin/path/bright down

username ALL=(root) NOPASSWD: BRIGHT_CMDS

EOF

exit 1

fi

# Gather information

backlight_dir='/sys/class/backlight'

device_dir=$(ls "${backlight_dir}" | head -n 1)

if [ -z "$device_dir" ]; then

echo 'No backlight hardware is listed in /sys/class/backlight! Quitting.'

exit 1

fi

device_dir="${backlight_dir}/${device_dir}"

brightness_file="${device_dir}/brightness"

curr_brightness=$(cat "${brightness_file}")

max_brightness=$(cat "${device_dir}/max_brightness")

if [ "$1" == 'current' ]; then

echo $( echo "(${curr_brightness} / ${max_brightness}) * 100" | bc -l) \

| cut -d'.' -f 1

else

direction=$1

# Calculate

step=$(( $max_brightness / 10 ))

if [ $direction == 'up' ]; then

new_brightness=$(( $curr_brightness + $step ))

elif [ $direction == 'down' ]; then

new_brightness=$(( $curr_brightness - $step ))

else

echo 'Argument $1 must be either "up" or "down". Quitting.'

exit 1

fi

# Limit range

if [ "$new_brightness" -gt "$max_brightness" ]; then

new_brightness="$max_brightness"

fi

if [ "$new_brightness" -lt 0 ]; then

new_brightness=0

fi

# "Do it" - the emperor

echo $new_brightness > "${brightness_file}"

fi

Usage

# Brightness up
$ sudo bright up

# Brightness down
$ sudo bright down

# Report current brightness level
$ bright current

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# Brightness up

$ sudo bright up

# Brightness down

$ sudo bright down

# Report current brightness level

$ bright current

If you’re going to bind this to some key combo, you may want to allow this to sudo without a password (as securely as possible).

# `sudo visudo` and add these lines to your sudoers
Cmnd_Alias BRIGHT_CMDS=/path/to/this/script/bright up, /path/to/this/script/bright down
your_user ALL=(root) NOPASSWD: BRIGHT_CMDS

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# `sudo visudo` and add these lines to your sudoers

Cmnd_Alias BRIGHT_CMDS=/path/to/this/script/bright up, /path/to/this/script/bright down

your_user ALL=(root) NOPASSWD: BRIGHT_CMDS

Here is my binding for i3wm

# Brightness controls
bindsym XF86MonBrightnessUp exec sudo /path/to/this/script/bright up; exec notify-send -t 1 "Brightness: $(/path/to/this/script/bright current)%"
bindsym XF86MonBrightnessDown exec sudo /path/to/this/script/bright down; exec notify-send -t 1 "Brightness: $(/path/to/this/script/bright current)%"

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# Brightness controls

bindsym XF86MonBrightnessUp exec sudo /path/to/this/script/bright up; exec notify-send -t 1 "Brightness: $(/path/to/this/script/bright current)%"

bindsym XF86MonBrightnessDown exec sudo /path/to/this/script/bright down; exec notify-send -t 1 "Brightness: $(/path/to/this/script/bright current)%"

So there you go!

2018.02.16

How we produce our podcast on Linux at Decipher SciFi

Christopher Peterson Blog Audacity, BASH, cli, FFmpeg, Instagram, Linux, podcasting

You may be a Linux podcasting person looking for some ideas after a couple of years of Linux podcast production. You may be a fan of Decipher SciFi who wants to see what it looks like on the back end. In either case, welcome!

This is not meant to be the guide to doing it right, but just a record of the hackey way that we do it for reference. It’s like looking at someone’s Vim config; you don’t just copy the thing, but take what is useful.

Our usual recording setup is the two of us in the same room with sporadic remote guest appearances via Skype. This is the stuff we use and how (links to products on Amazon may include an affiliate code 🙂 ).

Recording at the “studio” with Jolene Creighton for our Star Trek Beyond episode

Recording

Hardware

Microphones (ATR-2100)

The ATR-2100 microphone can use both USB and XLR

My partner and I both use ATR-2100 microphones. We settled on these for a few reasons:

Each has both XLR and USB interfaces, so we were able to continue to use them when graduating from computer to dedicated recorder.
They’re not overly sensitive so they work well when recording two people in the same room.
They’re affordable!

But, there is another. Since our mics and the system output from the Skype machine both go directly into the recorder, we need to have another microphone for our guests to hear us. We keep a Blue Yeti (which we do not recommend for the actual podcast recording) sitting in the middle of the table for this purpose, but whatever you have will probably do.

Recorder (Zoom H5)

We started out recording directly into the computer with Audacity which proved to ultimately be less than reliable. Maybe this could be a fine enough affordable option for one person, I suppose, but if you’re recording two people in the same room you have a lot of pain-in-the-ass fiddling with audio configurations to look forward to, iirc (to aggregate separate USB audio sources). After a while and a few disastrous software failures in this mode, we finally got a dedicated recorder. In fact, I would actually recommend a dedicated recorder no matter what platform you’re on.

Zoom H5 recorder

So, this thing. This thing is pretty great! It can record four channels – two single-channel XLR inputs on the bottom, and a combined stereo input from whatever “capsule” is plugged into the top. With the X/Y capsule (it ships with this one) on top we are able to plug in remote guests from a Skype session on the nearest computer and record all three tracks separately.

Our recording setup

Editing

Okay, finally on to some software stuff.

Convert

The H5 records in WAV, and can basically only record input from the capsule (Skype) in stereo. So I want to get these tracks into mono FLAC files because it is lossless without being huge.

Here is how I do this conversion (the current “production” version of this script can be found in my dotfiles).

#!/usr/bin/env bash                                                                                                     
                                                                                
# Requires:                                                                     
# ffmpeg                                                                        
                                                                                
# Usage                                                                         
if [ $# -eq 0 ]; then                                                           
  cat <<-EOF                                                                    
  Usage: $0 episode_dir file1 file2 file3...                                    
  Convert a bunch of WAVs to FLAC with names to match the target dir.           
  (For converting WAVs from the Zoom H5 into podcast tracks for editing by my   
  naming scheme)                                                                
                                                                                
    episode_dir | A directory named as the title of a podcast episode.          
    file1...n   | WAV files named with either a number or 'LR' as produced by   
                  the Zoom H5 recorder.                                         
EOF                                                                             
  exit 1                                                                        
fi                                                                              
                                                                                
episode_dir=$1                                                                  
files=("${@:2}")                                                                
moviename=$(basename "$episode_dir" | sed 's/^[0-9 ]*//')                       
                                                                                
mkdir -p "$episode_dir"                                                         
                                                                                
for file in "${files[@]}"; do                                                   
  num=$(echo "$file" | grep -Po '([0-9]|LR)(?=\.[wW][aA][vV])')                 
  num=$(echo "$num" | sed 's/LR/0/')                                            
  ffmpeg \                                                                      
    -i "$file" \                                                                
    -ac 1 \                                                                     
    "${episode_dir}/${moviename}.raw.${num}.flac"                               
done

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#!/usr/bin/env bash

# Requires:

# ffmpeg

# Usage

if [ $# -eq 0 ]; then

cat <<-EOF

Usage: $0 episode_dir file1 file2 file3...

Convert a bunch of WAVs to FLAC with names to match the target dir.

(For converting WAVs from the Zoom H5 into podcast tracks for editing by my

naming scheme)

episode_dir | A directory named as the title of a podcast episode.

file1...n | WAV files named with either a number or 'LR' as produced by

the Zoom H5 recorder.

EOF

exit 1

fi

episode_dir=$1

files=("${@:2}")

moviename=$(basename "$episode_dir" | sed 's/^[0-9 ]*//')

mkdir -p "$episode_dir"

for file in "${files[@]}"; do

num=$(echo "$file" | grep -Po '([0-9]|LR)(?=\.[wW][aA][vV])')

num=$(echo "$num" | sed 's/LR/0/')

ffmpeg \

-i "$file" \

-ac 1 \

"${episode_dir}/${moviename}.raw.${num}.flac"

done

Edit

Then I import the tracks into Audacity and go to town.

Here is my Audacity configuration and here are the plugins I use.

Post production

With the edit done, I can then run it through a final set of filters and cut in some intro and outro music (generously provided by Caelum Rale). Final export to 112kbps mono CBR LAME MP3 (plenty good enough for voice) with our id3 tags, add the thumbnail (Audacity doesn’t support this), and we’re done.

Final filters

We use Levelator because it works, still, and is at least free as in beer. It’s super old and out of support but it works just fine for us, so here it stays. You can get Levelator here, but the link to the Linux version is broken. The Windows version works superbly in Wine though!

Levelator is pretty easy to use

The alternative these days seems to be Auphonic, a web-based service that gives you a few free sessions per month or somesuch and is reasonably priced for more. It seems popular and I hear good things.

Thumbnail/cover art

Audacity doesn’t know how to write the cover art id3 tags, but it’s easily done on the cli anyway. eyeD3 is a good tool for this.

eyeD3 --add-image "/path/to/my/id3-tinylogo.jpg:FRONT_COVER" DecipherSciFi.mp3

1	eyeD3 --add-image "/path/to/my/id3-tinylogo.jpg:FRONT_COVER" DecipherSciFi.mp3

It’s not a big deal, but it’s nice to have.

Publishing

File Hosting

Our finalized MP3s get uploaded to Libsyn. Another good option I am happy to recommend is Blubrry. Either way, as an enterprising Linux nerd, you’d only be using it for file hosting because you’ll control the RSS feed itself from your own site? Right?

All kidding aside, people in the space continue to fight over whether you should control the feed from your own domain or relinquish control to the hosting service itself. You do you, but I prefer the former. And there’s a great WordPress plugin for that too mentioned below!

Website hosting

Our post for the episode then goes up on Decipher Scifi. The one good option here is WordPress(.org), really. How and where you do this is up to you but we run a multisite WordPress install on Linux on AWS and manage it ourselves. I do have a couple of tips re link shortening and Let’s Encrypt though if you’re into that sort of thing.

And then within WordPress, we use the only (and really good!) plugin for serving up podcast RSS feeds, Blubrry PowerPress. It’s never done us wrong.

Backups

Yeah don’t forget these! Both the audio and the website.

Audio backups

When the episode is up and out, we back up the raw tracks and the separate final edits of the tracks in FLAC, and the final cut in MP3. They go to Dropbox, Google Drive, S3, whatever, and a portable hard drive or two. The idea is to have both a local and remote copy if you value your backups.

The final edit files for one of our episodes

Website backups

I wrote a small hacky BASH script that does my WordPress backups. It tars and gzips both the entire WordPress directory and the database dump and then moves it around with Rsync. One day I’ll do the work of finding/creating a better, more robust solution. Let me know if you can recommend one?

Social

We have social channels! Twitter | Facebook | Instagram

Creating posts

Simple text posts are one thing, but I like to use images or video when possible. I use the following tools to help me with this.

GIMP. Here is my GIMP config, if you’re interested. As of writing, It is set to behave mostly sorta roughly like Photoshop, but I still haven’t tuned this up as much as I’d like. Caveat emptor.

Instagif is a script I wrote to convert GIF (from local or the web) to MP4 for Instagram. Facebook and Twitter both support GIF (though iirc they ultimately convert to MP4 anyway), but you need to handle Instagram differently and make the GIF into an MP4 that meets with Instagram’s length and color encoding requirements. Thus, the script. 🙂

Maybe I should just skip straight from GIF to MP4 for all the platforms? I’ll need to test to see if the viewing experience is diminished by this switch on Facebook and Twitter. Will report back.

Posting posts

Hootsuite!

The free tier of this wonderful service allows for scheduling up to 30 posts, which is more than I ever do at one time. And now it can even take advantage of Instagram’s direct-posting feature for business accounts, if you have one.

Summary

Hardware

Zoom H5 Recorder with a fast SD card
ATR-2100
Neewer NW-35 table-mounting mic arm. Super cheap and has been serving us with various heavy microphones for a good long while. It even holds up the super-heavy Blue Yeti which we used for a minute.

Software

Services

Decipher SciFi Bill & Ted selfie with Brandon Rollins

podcast on, dudes!

So there you have it. Amazon product links include our affiliate code, if you don’t mind helping us out a bit. Happy Linux podcasting! 😀

2018.02.13

Convert GIF to MP4 for Instagram with FFmpeg

Christopher Peterson Blog BASH, cli, code, FFmpeg, Instagram

I made a script to account for Instagram’s idiosynchracies when converting a GIF to MP4 using FFmpeg. Here it is:

https://github.com/cspeterson/dotfiles/blob/master/.bin/instagif

And now the details…

Doing a conversion of GIF to MP4 with ffmpeg seems like it should be simple enough:

ffmpeg -i something.gif out.mp4

1	ffmpeg -i something.gif out.mp4

But it isn’t! This can be insufficient in a couple of ways..

Problem 1: Video too short

Solution: Use a filter to loop the input enough times to meet the 3s minimum time requirement

-filter_complex "loop=<NUMBER_OF_LOOPS>"

1	-filter_complex "loop=<NUMBER_OF_LOOPS>"

Problem 2: Wrong color encoding

Given a color encoding that it doesn’t understand, Instagram just kinda poops out

Solution: By default, my ffmpeg used yuv444p, which Instagram wasn’t happy with. I haven’t done an exhaustive survey of the color encoding that Instagram will accept, but here is one: yuv420p.

-pix_fmt yuv420p

1	-pix_fmt yuv420p

In addition, the conversion requires the file’s height to be divisible by 2, so we need yet another filter:

-filter_complex "scale=trunc(iw/2)*2:trunc(ih/2)*2"

1	-filter_complex "scale=trunc(iw/2)2:trunc(ih/2)2"

Automation

Now since so many GIFs that I wish to post to Instagram are actually shorter than 3s, I automated everything above and here is the script. To see if I made any changes since posting this, check the version I’m currently using in my dotfiles.

#!/usr/bin/env bash

# Required:
# bc
# ffmpeg
# wget

set -e

# Usage
if [ $# -eq 0 ]; then
  cat <<-EOF
  Usage: $0 infile outfile
  Convert a gif to mp4 with ffmpeg, looping it enough times to ensure it meets
  Instagram's minimum video length limit.

    infile  | A valid gif file to convert. If given a URI, this script will
              try to download it for you and then convert it.
    outfile | A target filename for the result. If the output filename is not
              specified, it will be placed alongside the input file with the
              extension '.insta.mp4' added.
EOF
  exit 1
fi

# MAIN
INFILE=$1
OUTFILE=$2
MINTIME=3

# Download the input file if given a URI
urire='(https?|ftp|file)://[-A-Za-z0-9\+&@#/%?=~_|!:,.;]*[-A-Za-z0-9\+&@#/%=~_|]'
if [[ "${INFILE}" =~ "${urire}" ]]; then
  filename=$(basename "${INFILE}")
  wget -O "${filename}" "${INFILE}"
  INFILE="${filename}"
fi

# Determine output filename
if [ -z "${OUTFILE}" ]; then
  OUTFILE=$(echo "${INFILE}" | sed 's/\.gif$//')
  OUTFILE="${OUTFILE}.insta.mp4"
fi

# Check if input is gif
if [[ $(file "${INFILE}") != *GIF* ]]; then
  echo "Input file '${INFILE}' is not a gif. Quitting."
  exit 1
fi

# Get info on the gif
# (A simple -i or ffprobe would be sufficient to get the information we need for
# a video file, but not a gif. Basically as far as I can tell you need to
# process the file in a manner similar to this to get the frame count, and it
# then also provides us with the fps which we need anyway)
ffoutput=$(ffmpeg -i "${INFILE}" -f null /dev/null 2>&1)
framecount=$(echo "${ffoutput}" | grep -Po 'frame=\s+[0-9]+\s+' | egrep -o '[0-9]+')
vstreaminfo=$(echo "${ffoutput}" | grep -P 'Video:\s+gif')
fps=$(echo "${vstreaminfo}" | grep -Po '[0-9]+(?=\s+fps)')
# dims=$(echo "${vstreaminfo}" |  grep -Po '[0-9]+x[0-9]+')
# w=$(echo "${dims}" | cut -d 'x' -f 1)
# h=$(echo "${dims}" | cut -d 'x' -f 2)
len=$(echo "${framecount} / ${fps}" | bc -l | sed 's/0\{1,\}$//')
if (( $(echo "${len} >= 60" | bc -l ) == 1 )); then
  echo "Clip is too long for Instagram! The limit is 60s. Quitting."
  exit 1
fi

# How many loops do we need to meet instagram's min time? Round up with awk.
loops=$(echo "${MINTIME} / ${len}" | bc -l | awk '{print ($0-int($0)>0)?int($0)+1:int($0)}')

# Convert
ffmpeg -i "${INFILE}" \
       -filter_complex "loop=${loops}:32767:0,scale=trunc(iw/2)*2:trunc(ih/2)*2" \
       -f mp4 \
       -y \
       -preset slow \
       -pix_fmt yuv420p \
       "${OUTFILE}" >/dev/null 2>&1

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#!/usr/bin/env bash

# Required:

# bc

# ffmpeg

# wget

set -e

# Usage

if [ $# -eq 0 ]; then

cat <<-EOF

Usage: $0 infile outfile

Convert a gif to mp4 with ffmpeg, looping it enough times to ensure it meets

Instagram's minimum video length limit.

infile | A valid gif file to convert. If given a URI, this script will

try to download it for you and then convert it.

outfile | A target filename for the result. If the output filename is not

specified, it will be placed alongside the input file with the

extension '.insta.mp4' added.

EOF

exit 1

fi

# MAIN

INFILE=$1

OUTFILE=$2

MINTIME=3

# Download the input file if given a URI

urire='(https?|ftp|file)://[-A-Za-z0-9\+&@#/%?=~_|!:,.;]*[-A-Za-z0-9\+&@#/%=~_|]'

if [[ "${INFILE}" =~ "${urire}" ]]; then

filename=$(basename "${INFILE}")

wget -O "${filename}" "${INFILE}"

INFILE="${filename}"

fi

# Determine output filename

if [ -z "${OUTFILE}" ]; then

OUTFILE=$(echo "${INFILE}" | sed 's/\.gif$//')

OUTFILE="${OUTFILE}.insta.mp4"

fi

# Check if input is gif

if [[ $(file "${INFILE}") != *GIF* ]]; then

echo "Input file '${INFILE}' is not a gif. Quitting."

exit 1

fi

# Get info on the gif

# (A simple -i or ffprobe would be sufficient to get the information we need for

# a video file, but not a gif. Basically as far as I can tell you need to

# process the file in a manner similar to this to get the frame count, and it

# then also provides us with the fps which we need anyway)

ffoutput=$(ffmpeg -i "${INFILE}" -f null /dev/null 2>&1)

framecount=$(echo "${ffoutput}" | grep -Po 'frame=\s+[0-9]+\s+' | egrep -o '[0-9]+')

vstreaminfo=$(echo "${ffoutput}" | grep -P 'Video:\s+gif')

fps=$(echo "${vstreaminfo}" | grep -Po '[0-9]+(?=\s+fps)')

# dims=$(echo "${vstreaminfo}" | grep -Po '[0-9]+x[0-9]+')

# w=$(echo "${dims}" | cut -d 'x' -f 1)

# h=$(echo "${dims}" | cut -d 'x' -f 2)

len=$(echo "${framecount} / ${fps}" | bc -l | sed 's/0\{1,\}$//')

if (( $(echo "${len} >= 60" | bc -l ) == 1 )); then

echo "Clip is too long for Instagram! The limit is 60s. Quitting."

exit 1

fi

# How many loops do we need to meet instagram's min time? Round up with awk.

loops=$(echo "${MINTIME} / ${len}" | bc -l | awk '{print ($0-int($0)>0)?int($0)+1:int($0)}')

# Convert

ffmpeg -i "${INFILE}" \

-filter_complex "loop=${loops}:32767:0,scale=trunc(iw/2)*2:trunc(ih/2)*2" \

-f mp4 \

-y \

-preset slow \

-pix_fmt yuv420p \

"${OUTFILE}" >/dev/null 2>&1

Usage

To convert yup.gif to yup.mp4

instagif yup.gif yup.mp4

1	instagif yup.gif yup.mp4

To convert yup.gif into yup.insta.mp4

instagif yup.gif

1	instagif yup.gif

To create an insta.mp4 directly from a remote GIF

instagif https://media.giphy.com/media/lgcUUCXgC8mEo/giphy.gif insta.mp4

1	instagif https://media.giphy.com/media/lgcUUCXgC8mEo/giphy.gif insta.mp4

Happy giffing! 😀

2018.01.09

My intermediate Vim configuration and usage guide

Christopher Peterson Blog github, vim

This is my intermediate Vim configuration and usage guide.

It was aimed in particular at the newer Vim users at work, but someone else may get something from it too. Enjoy!

https://github.com/cspeterson/vim-guide-intermediate/blob/master/README.md