shell循环（国外英文资料）.doc

shell循环（国外英文资料） * * * * * * * * * While statement * * * * * * * * * General format: While the test conditions The do Command table The done = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = Example exam13. Sh #! / bin/sh While [$1] The do If [-f $1] Then echo display: $1 The cat $1 The else echo $1 is not a file name. fi The shift The done Right? Program function Right? How to test, add parameters = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = Example exam14. Sh #! / bin/sh Num = 1 While [$num - le 10] The do SUM = ` expr $num \ * $num ` Echo $SUM Num = ` expr ` $num + 1 The done Echo num = $num Right? Program function 1-10 Right? How to test, run directly = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = Example exam15. Sh #! / bin/sh Sum = 0 I = 0 While true The do I = ` expr $I + 1 ` Sum = ` expr $sum + $I ` If [$i-eq 100] then break fi The done Echo Sum is: $Sum Echo I is: $I Right? Program function: 1-100 cumulative Right? How to test, run directly = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = Example exam16 #! / bin/sh I = 10 While [$i-gt 5] The do Echo $I (I --) The done Echo $I For example, there are two things in the world * * * * * * * For statement * * * * * * * For example, this is the case for the problem Format 1: For variable in seq string The do The action The done Example exam17. Sh #! / bin/sh For I in $(seq 10) The do Echo $I The done Seq is the natural number seq 2, 10; 20 10 seq For example, this is the case for the problem Format 2: ((assignment; condition; operation statement)) The do The action The done. Example exam18. Sh #! / bin/sh (I = 1; I = 10; I + +)); The do Echo $I; The done. = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = =