问题
Why are the redirection operations in this command line apparently ignored by bash? I aim to redirect standard error to standard out, and then feed the whole lot into the void.
( cd ../src/ && python -m SimpleHTTPServer 8000 2>&1 > /dev/null ) &
I'm running a SimpleHTTPServer on some static web content, so that wget can check it for dead links. However, I don't want to see the errors from the server (requests for failed pages), as the wget log file provides all the information I need.
Nevertheless, when I run this...
( cd ../log/ && wget --quiet --spider --recursive -o spider.log http://localhost:8000/ 2>&1 > /dev/null )
...the original SimpleHTTPServer command running in the background carries on spewing out Standard Error reports about failed resource requests, like...
127.0.0.1 - - [28/May/2013 17:22:31] "GET /technology/actuator.html HTTP/1.1" 200 -
127.0.0.1 - - [28/May/2013 17:22:31] code 404, message File not found
回答1:
First both stdout(1) and stderr(2) point to your terminal.
You then redirect stderr to whatever your stdout points to. (Which is the terminal.)
Afterwards you redirect stdout to /dev/null. But stderr still points to the terminal.
You can do it the other way around >/dev/null 2>&1: This way you first redirect stdout to /dev/null and then stderr to the same.
Bash provides the shorthand &>/dev/null for this.
回答2:
Use &>/dev/null to suppress everything.
来源：https://stackoverflow.com/questions/16797139/how-do-i-suppress-output-from-this-shell-command