Thread: write headers from metadata

Dear Dr. Waddah,
Assuming you have you have a punch of SAC files (like 2009.*.SAC`) and you have a text file (for instance, called headinfo.txt ), containing the events information such as the following format, (where the columns written as EVLA EVLO EVDP MAG FILENAME):
-----------
25.0 37.0. 1.0 3.0 2009.139.17.30.58.0000.SG.HAQS..BHZ.D.SAC
25.1 37.1 1.5 3.1 2009.139.17.30.58.0000.SG.HQLS..BHZ.D.SAC
25.2 37.2 2.0 3.2 2009.139.17.30.58.0000.SG.MDRS..BHZ.D.SAC
25.3 37.3 2.5 3.3 2009.139.17.30.58.0000.SG.UMJS..BHZ.D.SAC
................etc
----------------
Then, one of the option is to use the following script which go through all sac files as in the list above and change any header info you would like to change.....
#####------------------Script starts here ----
#!/bin/bash
# rm ./prep_sacfile
files=`ls 2009*SAC`
for file in $files; do
olat=`cat headinfo.txt | grep "$file" | awk '{print $1}'`
olon=`cat headinfo.txt | grep "$file" | awk '{print $2}'`
dep=`cat headinfo.txt | grep "$file" | awk '{print $3}'`
mag=`cat headinfo.txt | grep "$file" | awk '{print $4}'`
ahlan=`echo $olat $olon $dep $mag | awk '{print $1,$2,$3,$4}'`
echo $ahlan
cat >> ./prep_sacfile << ENDSAC
r $file
ch evla $olat
ch evlo $olon
ch evdp $dep
ch mag $mag
wh
w over
ENDSAC
done
sac prep_sacfile
#####------------------Script ends here and you quit sac----
I hope this helps
Cheers, Mohammad Youssof