bash - 阻止bash脚本在终端中输出

Question

我相信我为if else语句正确设置了所有内容，但是它始终将内容输出到我的shell终端中，就像我自己运行命令一样。无论如何，我可以逃避这个问题，所以我可以运行这些命令，而无需在终端上填充结果文本？

#!/bin/bash
ps cax | grep python > /dev/null
if [ $? -eq 0 ]; then
  echo "Process is running." &
  echo $!
else
  echo "Process is not running... Starting..."
  python likebot.py &
  echo $!
fi

这是运行我的bash脚本几分钟后的输出结果

[~]# sh check.sh
Process is not running... Starting...
12359
[~]# Your account has been rated. Sleeping on kranze for 1 minute(s). Liked 0 photo(s)...
Your account has been rated. Sleeping on kranze for 2 minute(s). Liked 0 photo(s)...

Answer 1

如果要从shell脚本中重定向输出，请使用exec:

exec 1>/dev/null 2>&1

从现在开始，这将重定向所有内容。如果要输出到日志:

exec 1>/tmp/logfile 2>&1

追加日志:

exec 1>>/tmp/logfile 2>&1

要备份句柄，以便您可以还原它们:

exec 3>&1 4>&2
exec 1>/dev/null 2>&1

# Do some stuff

# Restore descriptors
exec 1>&3 2>&4

# Close the descriptors.
exec 3>&- 4>&-

如果脚本中有特定的部分，您希望保持静音:

#!/bin/bash

echo Hey, check me out, I can make noise!

{
    echo Thats not fair, I am being silenced!
    mv -v /tmp/a /tmp/b

    echo Me too.
} 1>/dev/null 2>&1