Member Avatar for ana_1234

I have to:
Run the grades program twice, so that it accepts the data in the files t1 and t2 as input for the two respective runs.

I ran the grades program, it asked me to enter digits, I have the t1 and t2 files, how do I make the program read the files with out coping and pasting the content of the file?

Send the output from these runs of the program to the output file

I still don't know how to do the first part so I just copied and pasted, the numbers from the file. but how do I sent the output to a output file?

Then Print a header to the output file before each run, with header text "Grades Test 1" and "Grades Test 2"

it should appear like this, Im so comfused
===================
Grades test 1
===================
[output from second test run of grades program]

===================
Grades test 2
===================
[output from second test run of grades program]

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  • Latest Post Latest Post by sree_ec

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wanted two runs of the grades program (feeding t1 then t2) with each run’s output recorded to a single file and a header before each run. The overwrite happened because the second run used > (which truncates). ’s idea of backgrounding with & will let two processes run at once, but that can cause races or interleaved output when they write to the same file. The simplest, reliable approach is to write a header then append the program output; capture stderr too if needed.

printf '===================\nGrades test 1\n===================\n' > output.txt
./grades < t1 >> output.txt 2>&1

printf '\n===================\nGrades test 2\n===================\n' >> output.txt
./grades < t2 >> output.txt 2>&1

To keep each header tightly paired with its run (one atomic redirect per run) use a grouped command so the header and program output go to the file together:

(printf '===================\nGrades test 1\n===================\n'; ./grades < t1) > output.txt
(printf '\n===================\nGrades test 2\n===================\n'; ./grades < t2) >> output.txt

If "capture the return" meant the process exit code, check $? immediately after the run and append it to the file:

./grades < t1 >> output.txt 2>&1
echo "Exit status (test 1): $?" >> output.txt

Notes: use >> to append (avoid overwriting), add 2>&1 to capture stderr, and replace ./grades with ./a.out or the actual executable name if different. If parallel execution is required, write each run to its own temp file and then concatenate (or use flock) to avoid races — otherwise run sequentially for predictable results.

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Member Avatar for ana_1234

I know I have to use the < and > operators but I have no clue how to capture the return of the program

Member Avatar for ana_1234

ok so I figured out how to run the program without copy and pasting but how do I run the grades program twice, so that it accepts the data in the files t1 and t2 as input for the two respective runs

Member Avatar for ana_1234

every time I try to put but t1 and t2 into the output.txt, t2 overwrites t1, HELP please

Member Avatar for sree_ec

every time I try to put but t1 and t2 into the output.txt, t2 overwrites t1, HELP please

#./a.out > outfile1.txt&
#./a.out > outfile2.txt

Note the & at the end of first command. It will run the first process in bg so that you can run the next process.
Is this what you wanted?

Edited by sree_ec because: n/a
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