带有多个管道的R-系统命令不会返回stdout。-R-systemcommandswithmultiplepipedonotreturnstdout

3  

Just replace \b with \\b and also be aware of [^grep] which matches any character but not of g or r or e or p.

只是替换\ b \ \ b也意识到(^ grep)匹配任何字符,但不是g或r e或p。

vLog <- system('ps -aux | grep -E "^.*\\b[^grep](python).*(runserver).*$" 2>/dev/null | tr -s " " | cut -d " " -f 2', intern = TRUE)

Example:

例子:

> system('ps -aux | grep -E "^.*\\bpython" 2>/dev/null | tr -s " " | cut -d " " -f 2', intern = TRUE)
[1] "2519" "2526" "3285" "3291"
> system('ps -aux | grep -E "^.*\bpython" 2>/dev/null | tr -s " " | cut -d " " -f 2', intern = TRUE)
character(0)