while循环似乎不记得变量更新-不涉及管道

debugcn 发表于 Dev

多项式

我正在使用标准Mate桌面运行LMDE 2（'Betsy'），并且具有以下脚本：

#!/bin/bash
# This script starts a specified terminal-binary in "Always on Top"-mode
# The assumption is, that 'wmctrl -l' sorts windows with the 
# in such a way, that the more recently a window has been created, 
# the lower it will be on the list ( compared to windows with the 
# same title).
#
# This is my assumption based on a short observation. The window 
# ids are probably given out in ascending hex numbers
# 
# Note: Using the pid will not help, since all terminals seem to
# be having the same pid
term_title_def='Terminal'
term_title='Terminal_top'
term_cmd="mate-terminal --title=$term_title"

# start terminal, wait for window  to appear and get id of most recently created window
# NOTE: a possible wrap-around of window ids has not been considered here!
eval $term_cmd
win_id=''
while [[ -z $win_id ]]; do
    win_id=$(wmctrl -l | grep "[[:blank:]]$term_title\$" | tail -n 1 | awk '{ print $1 }')
done

# DEBUG
touch /tmp/$win_id

# rename, set as "Always on top"
wmctrl -ir $win_id -T "$term_title_def"
wmctrl -ir $win_id -b add,above
wmctrl -ia $win_id

不知何故，脚本ps aufx在重启后首次从MATE-panel链接运行时，永远不会退出while循环（用进行检查）。后续调用按预期方式工作，即该链接完成了我想要的操作（请参阅上面的脚本注释）。

因此，我猜想在启动MATE之后立即以某种方式win_id无法在while-test中正确展开。或类似的东西。

这是为什么？
我现在将尝试类似的方法while true; do stuff; break; done，希望它能起作用...

更新：用以下内容
替换while上面的-loop

while true; do
    win_id=$(wmctrl -l | grep "[[:blank:]]$term_title\$" | tail -n 1 | awk '{ print $1 }')
    [[ $win_id ]] && break
done

没有改变任何东西。脚本仍然陷入无限循环...

芒登

我不知道这怎么工作。当你跑步

eval $term_cmd

您将打开一个终端窗口，脚本将不会执行任何其他操作，除非您将其关闭。您需要的是：

$term_cmd &

在后台运行它（不要使用eval，它是不需要的）。然后，您也不需要选择wmctrl输出的最后一行。，您正在设置终端标题，因此将其设置为唯一的grep内容：

#!/bin/bash
# This script starts a specified terminal-binary in "Always on Top"-mode
# The assumption is, that 'wmctrl -l' sorts windows with the 
# in such a way, that the more recently a window has been created, 
# the lower it will be on the list ( compared to windows with the 
# same title).
#
# This is my assumption based on a short observation. The window 
# ids are probably given out in ascending hex numbers
# 
# Note: Using the pid will not help, since all terminals seem to
# be having the same pid
term_title_def='Terminal'
term_title="Terminal_top_$$" ## Use the script's PID for a unique title
term_cmd="mate-terminal --title=$term_title"

## Start terminal. No need to wait, the loop will run until
## the terminal has been opened
$term_cmd &

win_id=''

while [[ -z "$win_id" ]]; do
    ## No need for '[[:blank:]]' and \$, you are using a unique title,
    ## keep the regex general. 
    win_id=$(wmctrl -l | grep "$term_title" | awk '{ print $1 }')
done
# DEBUG
touch /tmp/$win_id

# rename, set as "Always on top"
wmctrl -ir $win_id -T "$term_title_def"
wmctrl -ir $win_id -b add,above
wmctrl -ia $win_id