[SOLVED] Comparing variable with several lines of a column and if match take the value of the second column

Issue

I am with a problem with the Shell script to compare the value of a variable with thousands of values in a file. For example, supposing I have a variable

vel=8.14205

and I have a file with four columns but the most important its the two first columns,

7.9 white   7.90001 white   L
7.90001 white   7.90002 white   L
7.90002 white   7.90003 white   L
7.90003 white   7.90004 white   L
7.90004 white   7.90005 white   L
7.90005 white   7.90006 white   L
7.90006 white   7.90007 white   L
7.90007 white   7.90008 white   L
7.90008 white   7.90009 white   L
7.90009 white   7.9001  white   L
7.9001  white   7.90011 white   L
7.90011 white   7.90012 white   L
7.90012 white   7.90013 white   L
7.90013 white   7.90014 white   L
.
.
.
8.05034 gray81  8.05035 gray81  L
8.05035 gray81  8.05036 gray81  L
8.05036 gray81  8.05037 gray81  L
8.05037 gray81  8.05038 gray81  L
8.05038 gray81  8.05039 gray81  L
8.05039 gray81  8.0504  gray81  L
8.0504  gray81  8.05041 gray81  L
8.05041 gray81  8.05042 gray81  L
8.05042 gray81  8.05043 gray81  L
8.05043 gray81  8.05044 gray81  L
8.05044 gray81  8.05045 gray81  L
.
.
.
8.69995 black   8.69996 black   L
8.69996 black   8.69997 black   L
8.69997 black   8.69998 black   L
8.69998 black   8.69999 black   L
8.69999 black   8.7 black   B

if in some of the thousands of lines there is a line with

8.14205 gray84

then, I need to save it in another variable the "gray84".

Someone knows how can I do that?

I will be very grateful!

Solution

If you use the sample data that you provided in your question and add the line 8.14205 gray84, one awk option might be:

$ vel=8.14205
$ vel_color=$(awk -v vel="$vel" '{if ($1==vel) {print $2}}' src.dat)
$ echo "$vel_color"
gray84

Use the value stored in the vel variable to compare to the value in the first field. When there is a match print the second field.

Answered By - j_b

Answer Checked By - Willingham (WPSolving Volunteer)