使用bash读取特定文本并保存为.txt

Question

如何在读完.后读到__，并用bash将其保存到新的.txt文件中？

文件

 2021-01-12-1530.HUIG__002                                                 
 2021-01-12-1530.MEIG__002                                                 
 2021-01-12-1530.PCIG__002                                                 
 2021-01-12-1530.PEIG__002                                                 
 2021-01-12-1530.PNIG__002                                                 
 2021-01-12-1530.TGIG__002                                                 
 2021-01-12-1530.TOIG__002                                                 
 2021-01-12-1530.TPIG__002                                                 
 2021-01-12-1530.TXIG__002                                                 
 2021-01-12-1530.UXUV__002                                                 
 2021-01-12-1530.CCIG__002                                                 
 2021-01-12-1530.CMIG__002                                                 
 2021-01-12-1530.OXIG__002                                                 
 2021-01-12-1530.PLIG__002                                                 
 2021-01-12-1530.TUIG__002                                                 
 2021-01-12-1530.YAIG__002                                                 
 2021-01-12-1530.ZIIG__002                                                 
 2021-01-12-1530.FTIG__002                                                 
 2021-01-12-1530.NEUV__002                                                 
 2021-01-12-1530.TLIG__002                                                 
 2021-01-12-1530.YOIG__002                                                 
 2021-01-12-1530.DAIG__002                                                 
 2021-01-12-1530.HLIG__002                                                 

Answer 1

这是可行的：

$ head file1.txt 
2021-01-12-1530.HUIG__002                                                 
2021-01-12-1530.MEIG__002                                                 
2021-01-12-1530.PCIG__002                                                 
2021-01-12-1530.PEIG__002                                                 
2021-01-12-1530.PNIG__002                                                 
2021-01-12-1530.TGIG__002                                                 
2021-01-12-1530.TOIG__002                                                 
2021-01-12-1530.TPIG__002                                                 
2021-01-12-1530.TXIG__002                                                 
2021-01-12-1530.UXUV__002
$ cut -d. -f2 file1.txt | cut -d_ -f1 | head
HUIG
MEIG
PCIG
PEIG
PNIG
TGIG
TOIG
TPIG
TXIG
UXUV

并保存到新文件：

cut -d. -f2 file1.txt | cut -d_ -f1 > file2.txt

Answer 2

使用sed(1)

sed 's/^.*\.//;s/__.*$//' file.txt > new_file.txt

使用支持PCRE的GNU grep(1)

grep -Po '(?<=\.).*(?=__.*)' file.txt > new_file.txt