带有 cron 的 Gsettings [英] Gsettings with cron

问题描述

我编写了一个 bash 脚本来更改壁纸(适用于 GNOME3).

I wrote a bash script that changes the wallpaper (for GNOME3).

#!/bin/bash

# Wallpaper's directory.
dir="${HOME}/images/wallpapers/"

# Random wallpaper.
wallpaper=`find "${dir}" -type f | shuf -n1`

# Change wallpaper.
# http://bit.ly/HYEU9H
gsettings set org.gnome.desktop.background picture-options "spanned"
gsettings set org.gnome.desktop.background picture-uri "file://${wallpaper}"

在终端模拟器(例如 gnome-terminal)中执行的脚本效果很好.在 cron 或 ttyX 终端执行期间得到错误:

Script executed in a terminal emulator (eg gnome-terminal) works great. During the execution by cron, or ttyX terminal getting the error:

** (process:26717): WARNING **: Command line `dbus-launch --autolaunch=d64a757758b286540cc0858400000603 --binary-syntax --close-stderr' exited with non-zero exit status 1: Autolaunch error: X11 initialization failed.


** (process:26717): WARNING **: Command line `dbus-launch --autolaunch=d64a757758b286540cc0858400000603 --binary-syntax --close-stderr' exited with non-zero exit status 1: Autolaunch error: X11 initialization failed.


** (process:26721): WARNING **: Command line `dbus-launch --autolaunch=d64a757758b286540cc0858400000603 --binary-syntax --close-stderr' exited with non-zero exit status 1: Autolaunch error: X11 initialization failed.


** (process:26721): WARNING **: Command line `dbus-launch --autolaunch=d64a757758b286540cc0858400000603 --binary-syntax --close-stderr' exited with non-zero exit status 1: Autolaunch error: X11 initialization failed.

推荐答案

经过多次尝试，我终于设法解决了这个问题.

Finally I managed how to solve this issue after many, many attempts.

确实，出现这个问题是因为 cron 只使用了非常有限的一组环境变量.唯一一个负责以正确方式运行问题脚本的环境变量是 DBUS_SESSION_BUS_ADDRESS，而不是 DISPLAY 或 XAUTHORITY 或 GSETTINGS_BACKEND 或其他东西.这个答案也很好地指出了这一事实.

Indeed, the problem occur because cron uses only a very restricted set of environment variables. And the only one environment variable that is responsible for running in the right way the script from the question when this is set as a cron job is DBUS_SESSION_BUS_ADDRESS, not DISPLAY or XAUTHORITY or GSETTINGS_BACKEND or something else. This fact was also pointed well in this answer.

但是这个答案中的问题是不能保证来自 ~/.dbus/session-bus/ 目录中该文件的 DBUS_SESSION_BUS_ADDRESS 变量被更新为当前 gnome 会话的当前值.要解决这个问题，一种方法是在当前 gnome 会话中找到进程的 PID，并从其环境中获取 dbus 地址.我们可以这样做:

But the problem in this answer is that there's no guarantee that the DBUS_SESSION_BUS_ADDRESS variable from that file from ~/.dbus/session-bus/ directory is updated to the current value from the current gnome session. To go over this problem a method would be to find the PID of a process in the current gnome session, and obtain the dbus address from its environment. We can do this as follow:

PID=$(pgrep gnome-session)  # instead of 'gnome-session' it can be also used 'noutilus' or 'compiz' or the name of a process of a graphical program about that you are sure that is running after you log in the X session
export DBUS_SESSION_BUS_ADDRESS=$(grep -z DBUS_SESSION_BUS_ADDRESS /proc/$PID/environ|cut -d= -f2-)

话虽如此，脚本应该如下所示:

That being said, the script should look like:

#!/bin/bash

# TODO: At night only dark wallpapers.

# Wallpaper's directory.
dir="${HOME}/images/wallpapers/"

# export DBUS_SESSION_BUS_ADDRESS environment variable
PID=$(pgrep gnome-session)
export DBUS_SESSION_BUS_ADDRESS=$(grep -z DBUS_SESSION_BUS_ADDRESS /proc/$PID/environ|cut -d= -f2-)

# Random wallpaper.
wallpaper=`find "${dir}" -type f | shuf -n1`

# Change wallpaper.
# http://bit.ly/HYEU9H
gsettings set org.gnome.desktop.background picture-options "spanned"
gsettings set org.gnome.desktop.background picture-uri "file://${wallpaper}"

这篇关于带有 cron 的 Gsettings的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！