获取gphoto2的当前状态

Question

我使用--wait-event-and-download参数运行gphoto，这样我用红外线遥控器拍摄的照片就会保存到计算机上。

我设置了第二个脚本来中断等待进程并以编程方式拍照，如下所示：

#!/bin/sh
# shootnow.sh - stop the current gphoto2 process (if it exists),
# shoot a new image, then start a new wait-event process.

pkill -INT gphoto2     #send interrupt (i.e. ctrl+c) to gphoto2
sleep 0.1              #avoid the process ownership error
gphoto2 --capture-image-and-download  #take a picture now
gphoto2 --wait-event-and-download   #start a new wait-event process

但在中断之前，我想确保第一个等待事件进程当前没有下载图像(这会导致图像填满相机的ram，从而阻止进一步的操作)。因此，第二个脚本应该更像这样：

#!/bin/sh
# shootnow-with-check.sh - stop the current gphoto2 process (if it exists 
# and isn't currently downloading an image), shoot a new image, then start 
# a new wait-event process.

shootnow() {  # same as previously, but now in a function
    pkill -INT gphoto2
    sleep 0.1
    gphoto2 --capture-image-and-download
    gphoto2 --wait-event-and-download
}

if [ ***current output line of gphoto2 process doesnt start with "Downloading"*** ] then
    shootnow
else
    echo "Capture aborted - a picture was just taken and is being saved."
fi

有没有人能帮我写那个if语句？我可以读取正在运行的gphoto进程的当前输出行吗？

Answer 1

我最终通过一个脚本实现了这一点：

#!/bin/bash
# gphoto2-expect.sh
# use expect to monitor gphoto2 during --capture-image-and-download with
# --interval=-1, adding in SIGUSR1 functionality except during a
# download event.

echo "Prepping system for camera"
killall PTPCamera
expect << 'EOS'
puts "Starting capture..."
if [catch "spawn gphoto2 --capture-image-and-download --interval=-1" gp_pid] {
  Log $ERROR "Unable to start gphoto2.\n$gp_pid\n"
  return 0
}

trap {exec kill -SIGUSR1 $gp_pid} SIGUSR1
set timeout -1
expect {
  -i $spawn_id
  "Downloading" {
    trap {send_user "\n Ignoring request as currently downloading"} SIGUSR1 ; exp_continue
  }
  "Saving file as" {
    sleep 0.1
    trap {exec kill -SIGUSR1 $gp_pid} SIGUSR1 ; exp_continue
  }
}

EOS

这可以由另一个脚本触发：

#!/bin/bash
# trigger.sh - trigger an immediate capture
var=$(pidof expect)
kill -SIGUSR1 "$var"

Answer 2

gphoto2有一个选项--钩子脚本文件名。FILENAME必须是可执行脚本，并在某些gphoto2事件上调用。然后，该脚本具有一个环境变量ACTION，您可以将其用于您的目的。例如:您可以使用以下命令调用gphoto2

gphoto2 --capture-image-and-download --hook-script myhook.sh

myhook.sh看起来像是

#! /bin/bash
echo $ACTION

那么myhook.sh将被调用4次。它的输出是

init
start
download
stop

有关详细信息，请参阅man gphoto2。