awk check text file line-by-line

原创于 2016-10-16 12:34:36 发布 · 319 阅读

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本文介绍了一种使用awk脚本来验证文本文件是否精确包含预定义的三行内容（AA、BB、CC）的方法。通过awk的BEGIN和END部分以及NR变量来实现流程控制，确保文件内容完全匹配。

For example; using awk to check whether a text file has exactly following 3 lines:

    AA
    BB
    CC

awk script:

cat $infile | awk '
    BEGIN { retcode = 0; rowcount = 3 }
    NR==1 { if ( $0 != "AA") { retcode = NR; exit }}
    NR==2 { if ( $0 != "BB") { retcode = NR; exit }}
    NR==3 { if ( $0 != "CC") { retcode = NR; exit }}
    NR>rowcount { retcode = NR; exit }
    END { if (retcode != 0) exit retcode; else if (NR != rowcount) exit NR; else exit 0 }
'

Return Value:

=0: file is same

>0: the first line that is not matched.

Please be noticed:

1. the 'exit' statement in 'NR=X' rule will cause control flow come to 'END' section immediately.

2. use 'next' to continue next line