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adding a line to a text file

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# 1  
Old 06-10-2011
adding a line to a text file
I have a tab delimited text file,
Code:
id   name       distance
1    3325167    0.334561754018
2    3290488    0.389444269458
3    3288794    0.392312701782
4    3347602    0.392532202097
5    3295355    0.394394169485

I need to add a line after the header line. The first and third field of that added line with both be the value 0 (hard coded). The middle field will be from a bash variable.
Code:
id   name       distance
0    $BASH_VAR  0.0
1    3325167    0.334561754018
2    3290488    0.389444269458
3    3288794    0.392312701782
4    3347602    0.392532202097
5    3295355    0.394394169485

I have looked at solutions in both sed and awk and can't seem to find the right thing.

I tried,
Code:
awk 'BEGIN {FS="\t"} {if (NR==2) print "0", "\t", $NAME, "\t", "0.0"; else print $0; }' TEMP > $OUTFILE

But that garbles the values of the inserted and existing lines.

LMHmedchem
# 2  
Old 06-11-2011
Code:
% BASH_VAR=hello 

% cat testfile   
id   name       distance
1    3325167    0.334561754018
2    3290488    0.389444269458
3    3288794    0.392312701782
4    3347602    0.392532202097
5    3295355    0.394394169485

% sed '1a\       
0    '$BASH_VAR'  0.0' testfile
id   name       distance
0    hello  0.0
1    3325167    0.334561754018
2    3290488    0.389444269458
3    3288794    0.392312701782
4    3347602    0.392532202097
5    3295355    0.394394169485

If you need right columns try:
Code:
BASH_VAR=`printf '%-9s' hello`

This User Gave Thanks to yazu For This Post:
LMHmedchem
# 3  
Old 06-11-2011
I need tab delimited, so I got it to work with,

sed '1a\0\t'$BASH_VAR'\t0.0' TEMP > $OUTFILE

what is the meaning of the 1a\ notation? Does that mean to add the line at position 1? I thought you generally needed double quotes to preserve the value of the $VAR.

LMHmedchem
# 4  
Old 06-11-2011
Quote:
Does that mean to add the line at position 1?
Yes.
Quote:
I thought you generally needed double quotes to preserve the value of the $VAR.
Here it can work, but it won't in common case because sed and shell metachars can conflict (especially backslashes). So usual practice to embed shell variables in sed command is:
Code:
sed '...'$VAR'...'

Sorry for my English.
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