PHP command executes shell pin this report error

Reason for error: sort

Specific command grep ' download ' Test.log |awk ' {print $} ' |sort-r|uniq-c|sort-nr|head-n 10|less '

Error

Understand the words, help explain the reason, PS: The result of the implementation is correct.

Guess:
Sort first writes the contents of the file to a temporary file, and then sorts and writes the output results.

Additional notes:
Baidu on similar issues
Http://wapiknow.baidu.com/question/466815745.html

Reply content:

Reason for error: sort

Specific command grep ' download ' Test.log |awk ' {print $} ' |sort-r|uniq-c|sort-nr|head-n 10|less '

Error

Understand the words, help explain the reason, PS: The result of the implementation is correct.

Guess:
Sort first writes the contents of the file to a temporary file, and then sorts and writes the output results.

Additional notes:
Baidu on similar issues
Http://wapiknow.baidu.com/question/466815745.html

1. Where did your sort program come from? The GNU sort 8.24 has been confirmed not to report such noisy errors. In fact, the GNU coreutils have never been so dumb.

2. Calling from PHP, you don't have any sense to add less. Just 10 rows of data, do you use less meaningless?

Additional notes:
Baidu on the programming technology information is slag slag.

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