Parse file from certain line onwards in bash on Linux

Question

I have a CSV file containing the following registers:

Name,Phone,Country
John,N/A,USA
Max,N/A,USA

Name,Color,Size
John,Blue,M
Max,Red,S

How can I read only the registers from Name,Color,Size and onwards, using bash?

Additionally, how can I limit the output until it reaches either the EOF or a blank line? So this:

Name,Phone,Country
John,N/A,USA
Max,N/A,USA

Name,Color,Size
John,Blue,M
Max,Red,S

Dummy,Dummy,Dummy
Foo,Foo,Bar

Wouldn't output this:

John,Blue,M
Max,Red,S

Dummy,Dummy,Dummy
Foo,Foo,Bar

But rather only this:

John,Blue,M
Max,Red,S

I have already tried grep and sed but without luck, I also tried tail but the number of lines is unknown until the file is read.

Answer 1

Using awk

$ awk '/^$/{f=0} f{print} /Name,Color,Size/{f=1}' file
John,Blue,M
Max,Red,S

How it works

The awk script has one variable, f, which serves as a flag to identify when we are within a Name,Color,Size block.

• /^$/{f=0}

  On a blank line, set f=0 to signal that we are out of the Name,Color,Size block.

• f{print}

  When we are in the block, f==1, print the line.

• /Name,Color,Size/{f=1}

  When we reach the Name,Color,Size header, set f=1 to signal that we are in the block.

Using GNU sed

$ sed -n '/Name,Color,Size/{:a; n; /./{p; ba;}}' file
John,Blue,M
Max,Red,S

How it works

• -n

  Tell sed not to print anything unless we explicitly ask it to.

• /Name,Color,Size/{...}

  If the line contains the Name,Color,Size header, then execute the commands in the braces:

  • :a;

    This defines a label a.

  • n;

    This reads in the next line.

  • /./{p; ba;}

    If this next line is not blank, then print it (p) and branch (b) back to label a.

  In this way, all lines within the block will be read and printed and the printing stops with the first empty line.

Answer 2

You can use sed to show only the things after a certain line by doing something like

sed -e '0,/Name,Color,Size/d' <file>

so you'll only see the lines that come after Name,Color,Size