使用 bash 中的另一个文件替换 txt 文件中的多行

Question

I have two files "file1.txt" and "file2.txt" containing the same number of lines. I want to replace the odd lines of file2.txt by the odd lines of file1.txt.

Example:

file1.txt

header1.1
content1.1
header1.2
content1.2
header1.3
content1.3

file2.txt:

content2.1
header2.2
content2.2
header2.3
content2.3

The result I want:

file2.txt:

header1.1
content2.1
header1.2
content2.2
header1.3
content2.3

Thank you in advance

Answer 1

This will do it, assuming that header2.1 should be the first line of file2.txt .

I=1
paste -d '\n' file1.txt file2.txt | while read line ; do 
  if [ `expr \( $I + 3 \) % 4` -eq 0 ] ; then echo "$line" ; fi 
  if [ `expr  $I % 4` -eq 0 ] ; then echo $line ; fi 
  I=`expr $I + 1`
done

I'm using the paste -d '\n' file1.txt file2.txt to combine the 2 files into one stream with alternating lines that I then need to extract the correct row numbers. If you note that result of the paste looks something like:

[row 1] header1.1
[row 2] header2.1
[row 3] content1.1
[row 4] content2.1
[row 5] header1.2
[row 6] header2.2
[row 7] content1.2
[row 8] content2.2
....

It seems you want the odd lines of file1.txt and the even lines of file2.txt. In the combined example, you want row 1 and row 4 for each set of 4 rows.

This takes the line number, adds 3 and checks if that's divisible by 4 with no remainder by using the % (modulus) operator. This will match for row 1, row 5, row 9, etc.

expr \( $I + 3 \) % 4

This checks that the line number is divisible by 4

expr  $I % 4