Bash sample code: Create a speed test

42FileChecker features a speedtest for comparing two programs, here is how it works! (Note: This is not a reliable test)

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Sample code

# This function executes a command and returns the number of ouputted lines
# Returns -1 if the program has failed or terminated in less than $TIMEOUT
function speedtest_exec_command
{
    local COMMAND=$1              # The program to execute
    local TIMEOUT=30              # Duration of execution of the test
    local LOGFILE=.tmp_speedtest  # Temporary file to save outputs
    local TOTAL                   # Value to return

    # Execute, redirect outputs, send it to background and get PID
    ($COMMAND 1>$LOGFILE 2>&1) &
    local PID=$!

    # Wait for the duration and check if the process is still running
    sleep $TIMEOUT
    if [ ! -z "$(ps a | awk '{print $1}' | grep $PID)" ]
    then
        # If yes, stop the process...
        kill $PID
        wait $! 2>/dev/null

        # ...and count the number of lines written in the temporary file
        TOTAL=$(cat $LOGFILE | wc -l | sed 's/[^0-9]*//g')
    else
        # If not, the program has failed running the minimum duration
        TOTAL=-1
    fi

    rm -f $LOGFILE          # Remove the temporary file
    printf "%d" "$TOTAL"    # and print the returned value $TOTAL
}

# This is the main function that takes 3 arguments:
# - The name of the Student's program
# - The name of the original Unix program
# - The arguments to pass to each program on execution
function speedtest
{
    local PROG1=$1
    local PROG2=$2
    local ARGUMENTS=$3

    # Call the 'speedtest_exec_command' with the 1st program
    # and save the result in a variable $RET1
    echo "RUNNING: '$PROG1 $ARGUMENTS'"
    local RET1=`speedtest_exec_command "$PROG1 $ARGUMENTS"`
    echo "Total of lines: $RET1"

    # Call the 'speedtest_exec_command' with the 2nd program
    # and save the result in a variable $RET2
    echo "RUNNING: '$PROG2 $ARGUMENTS'"
    local RET2=`speedtest_exec_command "$PROG2 $ARGUMENTS"`
    echo "Total of lines: $RET2"

    # Calculate the ratio between $RET1 and $RET2 and print it
    local RATIO
    (( RATIO = $RET1 * 100 / $RET2 ))
    echo "\nRatio: $RATIO%"
}

# Call the speedtest (e.g: compare 'ft_ls' and 'ls')
speedtest "ft_ls" "ls" "-1R /"

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Tips

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Redirect outputs of a command line

declare LOGFILE_STDOUT=.standard_output
declare LOGFILE_STDERR=.standard_error

# Redirect STDOUT and STDERR to distinct files
cat * 1>$LOGFILE_STDOUT 2>$LOGFILE_STDERR

declare LOGFILE=.outputs

# Redirect STDOUT and STDERR to the same file
cat * 1>$LOGFILE 2>&1   # '&1' means 'to where the stream #1 is going'
cat * 2>$LOGFILE 1>&2   # The same result but inverted

cat * 2>&1 1>$LOGFILE   # Invalid order of redirections!

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Count the number of lines of a file

declare FILENAME=42FileChecker.sh

cat $FILENAME                               # Read the file
cat $FILENAME | wc -l                       # Display the number of lines
cat $FILENAME | wc -l | sed 's/[^0-9]*//g'  # Keep only the numeric value

# Now save the result in a numeric variable $TOTAL
declare -i TOTAL
TOTAL=$(cat $FILENAME | wc -l | sed 's/[^0-9]*//g')
echo "Number of lines: $TOTAL"

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Execute a command and save the result in a variable

function print_something
{
    printf "%s" "$1"
}

declare RETURN
RETURN=$(print_something "This is an argument")
RETURN=`print_something "This is an argument"`