6.5. awk Commands from Within a File
时间：2006-11-28 来源：h0ng123
6.5. awk Commands from Within a File
If awk commands are placed in a file, the –f option is used with the name of the awk file, followed by the name of the input file to be processed. A record is read into awk's buffer and each of the commands in the awk file is tested and executed for that record. After awk has finished with the first record, it is discarded and the next record is read into the buffer, and so on. If an action is not controlled by a pattern, the default behavior is to print the entire record. If a pattern does not have an action associated with it, the default is to print the record where the pattern matches an input line.
Example 6.10.
(The Database) $1 $2 $3 $4 $5 Tom Jones 4424 5/12/66 543354 Mary Adams 5346 11/4/63 28765 Sally Chang 1654 7/22/54 650000 Billy Black 1683 9/23/44 336500 % cat awkfile 1 /^Mary/{print "Hello Mary!"} 2 {print $1, $2, $3} % nawk –f awkfile employees Tom Jones 4424 Hello Mary! Mary Adams 5346 Sally Chang 1654 Billy Black 1683
EXPLANATION
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If the record begins with the regular expression Mary, the string Hello Mary! is printed. The action is controlled by the pattern preceding it. Fields are separated by whitespace.
The first, second, and third field of each record are printed. The action occurs for each line because there is not a pattern controlling the action.
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