Question

I’m writing a bash script called ‘run’ that tests programs with pre-defined inputs.

It takes in a file as the first parameter, then a program as a second parameter.

The call would look like

./run text.txt ./check

for example, the program ‘run’ would run ‘check’ with text.txt as the input. This will save me lots of testing time with my programs.

right now I have

$2 < text.txt > text.created

So it takes the text.txt and redirects it as input in to the program specified, which is the second argument. Then dumps the result in text.created.

I have the input in text.txt and I know what the output should look like, but when I cat text.created, it’s empty.

Does anybody know the proper way to run a program with a file as the input? This seems intuitive to me, but could there be something wrong with the ‘check’ program rather than what I’m doing in the ‘run’ script?

Thanks! Any help is always appreciated!

EDIT: the file text.txt contains multiple lines of files that each have an input for the program ‘check’.

That is, text.txt could contain

asdf1.txt
asdf2.txt
asdf3.txt

I want to test check with each file asdf1.txt, asdf2.txt, asdf3.txt.

Answer 1

A simple test with

#!/bin/sh

# the whole loop reads $1 line by line
while read
do
    # run $2 with the contents of the file that is in the line just read
    xargs < $REPLY $2
done < $1

works fine. Call that file “run” and run it with

./run text.txt ./check

I get the program ./check executed with text.txt as the parameters. Don’t forget to chmod +x run to make it executable.

This is the sample check program that I use:

#!/bin/sh

echo "This is check with parameters $1 and $2"

Which prints the given parameters.

My file text.txt is:

textfile1.txt
textfile2.txt
textfile3.txt
textfile4.txt

and the files textfile1.txt, … contain one line each for every instance of “check”, for example:

lets go

or

one two

The output:

$ ./run text.txt ./check
This is check with parameters lets and go
This is check with parameters one and two
This is check with parameters uno and dos
This is check with parameters eins and zwei