a shell wrapper to pull org.gnome.proxy settings into env, e.g. http_proxy, which is useful for .desktop files

gnome_proxy_to_env.md

Why?

Useful for:

• updating current terminal's shell env proxy settings, or
• wrapping exec in .desktop files to inject env proxy settings

GNOME proxy settings should normally get propergated into the shell (bash) environment via gnome-terminal, e.g. http_proxy and no_proxy. However:

• I noticed that applications exectuted via .desktop entries sometimes don't work. This happens when an app ignores org.gnome.proxy settings but can often use proxy env vars from the shell.
• If you're proxy settings change, existing shell processes will still have the old proxy enviroment variables, so this can help refresh them whithout having to create a new shell.

How?

Telegram .desktop file example

See #2777 for Telegram Desktop. Bascially:

• It's defaults works with http_proxy when executed via a shell
• It's defaults don't work via the telegramdesktop.desktop file

E.g. if avaialbe via $PATH:

...
Exec=gnome_proxy_to_env.sh Telegram -- %u
...

Bash

Sourcing the proxy settings into a current shell (changes current shell's proxy env vars)

$ source gnome_proxy_to_env.sh
$ grep http_proxy
http_proxy=http://localhost:8080

Wrap a command (doesn't change current shell's proxy proxy env vars, only called shell subprocess)

$ ./gnome_proxy_to_env env.sh | grep http_proxy
http_proxy=http://localhost:8080

gnome_proxy_to_env.sh

#!/usr/bin/env bash

# Deal with some proxy pain for Linux apps! Note:
# - Default is let desktop env manage proxy env
# - However, GNOME does't always set the proxy enviroment when an application is
#   executed via a .desktop file #sadpanda
# - This tries to help pull org.gnome.proxy settings into http_proxy, etc
# - `gsettings list-recursively org.gnome.system.proxy`

set -e

function un_single_quote() {
  s="$1"
  s=${s%\'}
  s=${s#\'}
  echo "$s"
}

function proxy_on() {
  # http org.gnome.system.proxy.http
  http_host="$(un_single_quote "$(gsettings get org.gnome.system.proxy.http host)")"
  http_port="$(un_single_quote "$(gsettings get org.gnome.system.proxy.http port)")"
  export http_proxy="http://$http_host:$http_port"
  export HTTP_PROXY=$http_proxy
  # org.gnome.system.proxy.https
  https_host="$(un_single_quote "$(gsettings get org.gnome.system.proxy.https host)")"
  https_port="$(un_single_quote "$(gsettings get org.gnome.system.proxy.https port)")"
  export https_proxy="https://$https_host:$https_port"
  export HTTPS_PROXY=$https_proxy
  # org.gnome.system.proxy.ftp
  ftp_host="$(un_single_quote "$(gsettings get org.gnome.system.proxy.ftp host)")"
  ftp_port="$(un_single_quote "$(gsettings get org.gnome.system.proxy.ftp port)")"
  export ftp_proxy="ftp://$ftp_host:$ftp_port"
  export FTP_PROXY=$ftp_proxy
  # socks org.gnome.system.proxy.socks
  # TODO: not proccessed for now
  # org.gnome.system.proxy ignore-hosts
  ignore_hosts="$(gsettings get org.gnome.system.proxy ignore-hosts)"
  no_proxy="${ignore_hosts:1:-1}"
  no_proxy="${no_proxy// /}"
  no_proxy="${no_proxy//\'/}"
  export no_proxy
  export NO_PROXY=$no_proxy
}

function proxy_off() {
    unset no_proxy
    unset NO_PROXY
    unset http_proxy
    unset HTTP_PROXY
    unset https_proxy
    unset HTTPS_PROXY
    unset ftp_proxy
    unset FTP_PROXY
}

# check for unsupported settings
case "$(un_single_quote "$(gsettings get org.gnome.system.proxy mode)")" in
  manual)
    proxy_on
    ;;
  auto)
    echo "ERROR: Auto, autoconfig-url (PAC) is not yet supported" >&2
    exit 1
    ;;
  none)
    proxy_off
    ;;
  *)
    echo "ERROR: org.gnome.system.proxy mode unknown" >&2
    exit 1
    ;;
esac
if [[ "$(gsettings get org.gnome.system.proxy.http use-authentication)" == 'true' ]]; then
  echo "ERROR: HTTP proxy authentication is not yet supported" >&2
  exit 1
fi

# if not sourced, then wrap
if ! [[ "${BASH_SOURCE[0]}" != "${0}" ]]; then
  if [ -z "$1" ] || [ "$1" == '-h' ] || [ "$1" == '--help' ] ; then
    echo 'Usage:'
    echo ' - This can be sourced, e.g.'
    echo '   `. gnome_proxy_to_env.sh; <command>`'
    echo ' - Or can wrap the command, e.g.'
    echo '   `./gnome_proxy_to_env.sh <command/application>``'
  elif [ "$#" -gt 0 ]; then
    exec $@
  fi
fi