shell 命令讀文件行

• 源文件內容

文件名	文件內容
file2_part.txt	name5 data15 dada16 name3 data9 dada10 data11 dada12

• for命令讀取的行結果被空格符分開了

root@ae02635267dc:/workspace/autohome/test/shell/awk# for line in `cat file2_part.txt`;do echo $line;done;
name5
data15
dada16
name3
data9
dada10
data11
dada12

• while命令

root@ae02635267dc:/workspace/autohome/test/shell/awk# while read line; do echo $line;done <file2_part.txt 
name5 data15 dada16
name3 data9 dada10 data11 dada12

• 應用場景：以文件B的行爲待查找內容，然後從A文件中搜索指定數量的內容 

while read line; do grep "$line" $A.txt|shuf|head -n 5;done <$B.txt >>rst.txt

參考文獻：

1. 'for LINE in $(cat file)' breaking at spaces, not just newlines