CODEWITHSUNDEEP
bashshellconditional-statements
fred
fred

Reputation: 23

BASH script conditional statement issues

I'm trying to use a Bash script to run a large number of calculations (just over 2 million) using a terminal-based program called uvspec. But I've hit a serious barrier following the latest addition to the calculation...

The script, opens an input file which has 2e^6 lines looking like this:

0 66.3426 -9.999 -9999
0 66.6192 -9.999 -9999
0 61.9212 1.655 1655
0 61.9999 1.655 1655
...

Each of these values represents a different value I want to substitute into the input file (using sed), so I read each line into an array. Many of these lines contain negative values in the 4th column e.g. -9999, which result in errors in the program so I would like to omit those lines and return a standard output - I'm doing this with the if statement... Problem is something terribly wrong is coming out of my output and I'm 99.9% sure the problem is a mistake in the following script as I'm fairly new to bash.

Can anyone spot anything here that doesn't make sense or is bad syntax?

Any comments on the script in general would also be useful feedback.

cat ".../Maps/dniinput" | while IFS=$' ' read -r -a myArray
do  
if [ "${myArray[3]}" -gt 0 ]
    then
      sed s/TAU/"${myArray[0]}"/ x.template x.template > a.template
      sed s/SZA/"${myArray[1]}"/ a.template a.template > b.template
      sed s/ALT/"${myArray[2]}"/ b.template b.template > x.inp
       ../bin/uvspec < x.inp >> dni.out

 else
     echo "0 -9999" >> dnijul.out
 fi 
done

Upvotes: 1

Views: 154

Answers (2)

Mark Setchell
Mark Setchell

Reputation: 207395

Sed can do all three substitutions in one go and you can pipe the output straight into your analysis program without creating any intermediate a.template and b.template files... 

sed -e "s/.../.../" -e "s/.../.../" -e "s/.../.../" x.template | ../bin/uvspec

By the way, you can also get rid of the "cat" at the start, and replace your array with variables whose names better match what they are, if you use a loop like this:

while IFS=S' ' read tau sza alt p4
do
   echo $tau $sza $alt $p4
done < a
0 66.3426 -9.999 -9999
0 66.6192 -9.999 -9999
0 61.9212 1.655 1655
0 61.9999 1.655 1655

I named the fourth element "p4" because you refer to the 4th one as the altitude in your comment, but in your code you replace the word "ALT" with the third column - so I am not really sure what your parameters are, but you should hopefully get the idea from the example above.

Upvotes: 2

BRPocock
BRPocock

Reputation: 13914

You might want to combine those "sed" lines into something more like:

 sed -e "s/TAU/${myArray[0]}/" -e "s/SZA/${myArray[1]}/" \
     -e "s/ALT/${myArray[2]}/" < x.template \
   | ../bin/uvspec >> dni.out

Upvotes: 0

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