从bash脚本中的文件读取多行

Question

I would like to be able to read groups of lines from a file within a bash script. The following code prints the first line of a file twice

   #!/bin/bash
   filename=$1
   read -r line < "$filename"
   echo $line
   read -r line < "$filename"
   echo $line

whereas I would like to print the second line. The following code prints ALL lines of a file

   #!/bin/bash
   filename=$1
   while read -r line
   do
      echo $line
   done < "$filename"

but in a more complicated script I don't want to insert the convoluted logic to do different tasks while being forced to read every line from a file one at a time. Can someone suggest a way to do something like

   # Read in a line from a file.
   # Do something with that line.
   #
   # Read in the next 5 lines from the file.
   # Do something different with those lines.
   #
   # etc.

Thanks.

Answer 1

Wrap the whole code in a block that's redirected from the file:

{
    read line
    // do something with $line
    ...
    read line2
    // do something with $line2
    ...
} < "$filename"