我试着跟着做，发现它也有用，

command > /dev/null 2>&1 | grep 'something'

对于那些想要将stdout和stderr永久重定向到文件的人，在stderr上使用grep，但保留stdout以将消息写入tty:

# save tty-stdout to fd 3
exec 3>&1
# switch stdout and stderr, grep (-v) stderr for nasty messages and append to files
exec 2> >(grep -v "nasty_msg" >> std.err) >> std.out
# goes to the std.out
echo "my first message" >&1
# goes to the std.err
echo "a error message" >&2
# goes nowhere
echo "this nasty_msg won't appear anywhere" >&2
# goes to the tty
echo "a message on the terminal" >&3

在Bash中，你也可以使用进程替换重定向到子shell:

command > >(stdout pipe)  2> >(stderr pipe)

对于手头的案子:

command 2> >(grep 'something') >/dev/null

把这些最好的答案结合起来，如果你有:

命令2> >(grep -v something 1>&2)

.．.然后所有的stdout被保留为stdout，所有的stderr被保留为stderr，但是你不会在stderr中看到任何包含字符串“something”的行。

这有一个独特的优点，即不反转或丢弃stdout和stderr，也不将它们混在一起，也不使用任何临时文件。

我刚刚提出了一个解决方案，使用命名管道将stdout发送到一个命令，stderr发送到另一个命令。

在这里。

mkfifo stdout-target
mkfifo stderr-target
cat < stdout-target | command-for-stdout &
cat < stderr-target | command-for-stderr &
main-command 1>stdout-target 2>stderr-target

之后删除已命名的管道可能是个好主意。

首先将stderr重定向到stdout -管道;然后将stdout重定向到/dev/null(不改变stderr的去向):

command 2>&1 >/dev/null | grep 'something'

有关各种I/O重定向的详细信息，请参阅Bash参考手册中的重定向章节。

Note that the sequence of I/O redirections is interpreted left-to-right, but pipes are set up before the I/O redirections are interpreted. File descriptors such as 1 and 2 are references to open file descriptions. The operation 2>&1 makes file descriptor 2 aka stderr refer to the same open file description as file descriptor 1 aka stdout is currently referring to (see dup2() and open()). The operation >/dev/null then changes file descriptor 1 so that it refers to an open file description for /dev/null, but that doesn't change the fact that file descriptor 2 refers to the open file description which file descriptor 1 was originally pointing to — namely, the pipe.