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       GNU coreutils çå¨çº¿å¸®å©ï¼ <http://www.gnu.org/software/coreutils/>
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       Copyright © 2017 Free Software Foundation, Inc.  License GPLv3+: GNU
       GPL version 3 or later <http://gnu.org/licenses/gpl.html>.
       This is free software: you are free to change and redistribute it.
       There is NO WARRANTY, to the extent permitted by law.

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GNU coreutils 8.28                2017å¹´10æ                           EXPR(1)