Knowledge Point
In linux, there are three commonly used IO device
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0: stdin represents the standard input. Similarly System.in.scan Java () in the receiving user information from the keyboard, the input device is transmitted to the label
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1: represents the stdout standard output. Similar in Java System.out.print (), the output to the standard output device!
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2: represents the standard error stderr. Similar in Java System.err.print (xx), the output information to the error output device!
Usually we use the command
pwd> a.txt
equivalent to
pwd . 1> a.txt
Precautions: faefafeafca 1> c.log 2> c.log effect equivalent to faefafeafca 1> d.log 2> & 1, but there are differences
faefafeafca 1> c.log 2> c.log opens c.log file twice!
faefafeafca 1> d.log 2> & 1 will only open c.log files at once! efficient! Recommended!
The final command
20 is log.jar. 1. 5 JAR Java> / dev / null 2> &. 1 & # # & representative of the last background