如何隔行读取一个文件

slwj

各位好，遇到个问题，想隔行读取一个文件，也就是说，只读取它的奇数行或者偶数行，该如何处理，多谢！

ly5066113

回复 1# slwj

1. seq 10 | sed '0~2d'
   
2. seq 10 | sed '1~2d'

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A_Traveler

1. seq 10|awk 'i=!i'

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1. seq 10|awk '!(i=!i)'

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slwj

回复 3# A_Traveler
要隔行读取特定文件filename的，哪里放入这个文件名呢


   

Herowinter

回复 4# slwj

1. sed '0~2d' filename
   
2. 
   
3. sed '1~2d' filename
   

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waker

2old写法
sed 'n;d'
sed '1d;n;d'

A_Traveler

回复 4# slwj

1. awk 'i=!i' filename

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1. awk '!(i=!i)' filename

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stupid_lee

ly5066113 发表于 2015-05-26 15:26
回复 1# slwj
seq 10 | sed '0~2d'

seq 10 | sed '1~2d'

Tim哥能否解释下这种sed用法呢

ly5066113

回复 8# stupid_lee

info sed

`FIRST~STEP'
     This GNU extension matches every STEPth line starting with line
     FIRST.  In particular, lines will be selected when there exists a
     non-negative N such that the current line-number equals FIRST + (N
     * STEP).  Thus, to select the odd-numbered lines, one would use
     `1~2'; to pick every third line starting with the second, `2~3'
     would be used; to pick every fifth line starting with the tenth,
     use `10~5'; and `50~0' is just an obscure way of saying `50'.