Question

I am aware, that this problem has been asked in slightly different ways many times before. But I couldn’t adapt those solutions.
I am having a file header.out with the following content:

// some text before this 
            :type = "Primary Grid: Tau Format" ;
            :deformation_timestep = 0. ;
            :deformation_alpha = 0. ;
            :deformation_dalpha = 0. ;
            :deformation_h = 0. ;
            :deformation_dh = 0. ;
            :deformation_step = 0 ;
            :adaptation_level = 0 ;
            :connectivity_check = 1 ;
            :volume_check = 1 ;
            :point_check = 1 ;
            :test_lib_check = 1 ;
            :periodic_pairs_check = 1 ;
            :is_balanced = 0 ;
            :preserve_piles = 0 ;
            :marker_1 = "WingMidTrailing" ;
            :marker_2 = "WingMidLower" ;
            :marker_3 = "WingMidUpper" ;
            :marker_4 = "WingSide" ;
            :marker_5 = "Farfield" ;
            :marker_6 = "SymmetryPlane" ;
            :marker_7 = "WingInnerLower" ;
            :marker_8 = "WingInnerUpper" ;
            :marker_9 = "WingInnerTrailing" ;
            :marker_10 = "WingOuterLower" ;
            :marker_11 = "WingOuterUpper" ;
            :marker_12 = "WingOuterTrailing" ;
 }

I need to extract the ID of the marker that belongs to the string “SymmetryPlane”
So in this case i want to have 6 as the output. All tries using sed and regular expressions failed.
What i have tried is:

sed 's/.*marker_\(.*\) = "SymmetryPlane.*/\1/' header.out

But this only gives me

            :type = "Primary Grid: Tau Format" ;
            :deformation_timestep = 0. ;
            :deformation_alpha = 0. ;
            :deformation_dalpha = 0. ;
            :deformation_h = 0. ;
            :deformation_dh = 0. ;
            :deformation_step = 0 ;
            :adaptation_level = 0 ;
            :connectivity_check = 1 ;
            :volume_check = 1 ;
            :point_check = 1 ;
            :test_lib_check = 1 ;
            :periodic_pairs_check = 1 ;
            :is_balanced = 0 ;
            :preserve_piles = 0 ;
            :marker_1 = "WingMidTrailing" ;
            :marker_2 = "WingMidLower" ;
            :marker_3 = "WingMidUpper" ;
            :marker_4 = "WingSide" ;
            :marker_5 = "Farfield" ;
6
            :marker_7 = "WingInnerLower" ;
            :marker_8 = "WingInnerUpper" ;
            :marker_9 = "WingInnerTrailing" ;
            :marker_10 = "WingOuterLower" ;
            :marker_11 = "WingOuterUpper" ;
            :marker_12 = "WingOuterTrailing" ;
}

I am not sure why this is happening.

Thanks in advance!

Answer 1

Just suppress the output (-n) and print after substitution (p):

sed -n 's/.*marker_\(.*\) = "SymmetryPlane.*/\1/p' header.out