Software Construction

#include <stdio.h>

// print arguments to stdout
int main(int argc, char *argv[]) {

    for (int i = 1; i < argc; i++) {
        if (i > 1) {
            fputc(' ', stdout);
        }
        fputs(argv[i], stdout);
    }
    fputc('\n', stdout);

    return 0;
}

import sys


def main():
    """
    print arguments to stdout
    """
    print(' '.join(sys.argv[1:]))


if __name__ == '__main__':
    main()

import sys
print(f'sys.argv = {sys.argv}')

echo My name is "$0"
echo My process number is $$
echo I have $# arguments

echo My command-line arguments are "$@"

echo My 5th argument is "'$5'"
echo My 10th argument is "'${10}'"

for a in "$@"
do
  echo "$a"
done

ls -las "$@"

cat "$@" |                   # tr doesn't take filenames as arguments
tr 'A-Z' 'a-z'|              # map uppercase to lower case, better - tr '[:upper:]' '[:lower:]'
tr ' ' '\n' |                # convert to one word per line
tr -cd "a-z'" |              # remove all characters except a-z and '
grep -E -v '^$' |            # remove empty lines
sort |                       # place words in alphabetical order
uniq -c |                    # count how many times each word occurs
sort -rn                     # order in reverse frequency of occurrence

# notes:
# - first 2 tr commands could be combined
# - sed 's/ /\n/g' could be used instead of tr ' ' '\n'
# - sed "s/[^a-z']//g" could be used instead of tr -cd "a-z'"

last=$1

number=1
while test $number -le "$last"
do
    echo $number
    number=$((number + 1))
done

if test $# = 1
then
    first=1
    last=$1
elif test $# = 2
then
    first=$1
    last=$2
else
    echo "Usage: $0 <last> or  $0 <first> <last>" 1>&2
    exit 1
fi

number=$first
while test $number -le "$last"
do
    echo $number
    number=$((number + 1))
done

if [ $# = 1 ]
then
    first=1
    last=$1
elif [ $# = 1 ]
then
    first=$1
    last=$2
else
    echo "Usage: $0 <last> or  $0 <first> <last>" 1>&2
    exit 1
fi

number=$first
while [ $number -le $last ]
do
    echo $number
    number=$((number + 1))
done

repeat_seconds=300  #check every 5 minutes

if test $# = 3
then
    url=$1
    regexp=$2
    email_address=$3
else
    echo "Usage: $0 <url> <regex> <email-address>" 1>&2
    exit 1
fi

while true
do
    if curl --silent "$url"|grep -E "$regexp" >/dev/null
    then
        # the 2nd echo is for testing, remove to really send email
        echo "Generated by $0" |
        echo mail -s "website '$url' now matches regex '$regexp'" "$email_address"
        exit 0
    fi
    sleep $repeat_seconds
done

if test $# = 0
then
    echo "Usage $0: <files>" 1>&2
    exit 1
fi

for filename in "$@"
do
    new_filename=$(
        echo "$filename"|
        tr '[:upper:]' '[:lower:]'
        )

    test "$filename" = "$new_filename" &&
        continue

    if test -r "$new_filename"
    then
        echo "$0: $new_filename exists" 1>&2
    elif test -e "$filename"
    then
        mv -- "$filename" "$new_filename"
    else
        echo "$0: $filename not found" 1>&2
    fi

done

echo -n "Do you like learning Shell? "
read answer

# get first letter of answer connverted to lower case
answer="$(
    echo "$answer"|
    cut -c1|
    tr A-Z a-z
    )"

if test "$answer" = "y"
then
    response=":)"
elif test "$answer" = "n"
then
    response=":("
else
    response="??"
fi

echo "$response"

for file in "$@"
do
    while IFS= read -r line
    do
        echo "$line"
    done <$file
done

echo -n "Do you like learning Shell? "
read answer

case "$answer" in
[Yy]*)
    response=":)"
    ;;

[Nn]*)
    response=":("
    ;;

*)
    response="??"
esac

echo "$response"

cat >main.c <<'eof'
#include <stdio.h>

int main(void) {
    int v = 0 ;
eof

i=0
while test $i -lt 1000
do
    # add a line to main.c to call the function f$i

    cat >>main.c <<eof
    int f$i(void);
    v += f$i();
eof

    # create file$i.c containing function f$i

    cat >file$i.c <<eof
int f$i(void) {
    return $i;
}
eof

    i=$((i + 1))
done

cat >>main.c <<'eof'
    printf("%d\n", v);
    return 0;
}
eof

# compile and run the 1001 C files
time clang main.c file*.c
./a.out

favourite_command() {
    name=$1
    command=$2
    echo "My name is $name, my favourite Unix command is $command."
}

favourite_command Andrew "uniq"
favourite_command Dylan "jq"
favourite_command Grace "sed"

is_prime() {
    local n i
    n=$1
    i=2
    while test $i -lt $n
    do
        test $((n % i)) -eq 0 &&
            return 1
        i=$((i + 1))
    done
    return 0
}

i=0
while test $i -lt 1000
do
    is_prime $i &&
        echo $i
    i=$((i + 1))
done

is_prime() {
    local n i
    n=$1
    i=2
    while ((i < n))
    do
        if ((n % i == 0))
        then
            return 1
        fi
        i=$((i + 1))
    done
    return 0
}

i=0
while ((i < 1000))
do
    is_prime $i && echo $i
    i=$((i + 1))
done

for file1 in "$@"
do
    for file2 in "$@"
    do
        test "$file1" = "$file2" &&
            break # avoid comparing pairs of assignments twice

        if diff -iBw "$file1" "$file2" >/dev/null
        then
            echo "$file1 is a copy of $file2"
        fi

    done
done

TMP_FILE1=/tmp/plagiarism_tmp1$$
TMP_FILE2=/tmp/plagiarism_tmp2$$


for file1 in "$@"
do
    for file2 in "$@"
    do
        test "$file1" = "$file2" &&
            break # avoid comparing pairs of assignments twice

        sed 's/\/\/.*//' "$file1" >$TMP_FILE1
        sed 's/\/\/.*//' "$file2" >$TMP_FILE2

        if diff -i -w $TMP_FILE1 $TMP_FILE2 >/dev/null
        then
            echo "$file1 is a copy of $file2"
        fi

    done
done

rm -f $TMP_FILE1 $TMP_FILE2

TMP_FILE1=$(mktemp)
TMP_FILE2=$(mktemp)

# trap allows use to remove temporary files if program interrupted
trap 'rm -f $TMP_FILE1 $TMP_FILE2' EXIT

# s/"["]*"/s/g changes strings to the letter 's'
# It won't match a few C strings which is OK for our purposes

# s/[a-zA-Z_][a-zA-Z0-9_]*/v/g changes variable names to 'v'
# It will also change function names, keywords etc. which is OK for our purposes.

transform() {
    sed '
        s/\/\/.*//
        s/"[^"]"/s/g
        s/[a-zA-Z_][a-zA-Z0-9_]*/v/g
        ' $1
}

for file1 in "$@"
do
    for file2 in "$@"
    do
        test "$file1" = "$file2" &&
            break # avoid comparing pairs of assignments twice

        transform "$file1" >$TMP_FILE1
        transform "$file2" >$TMP_FILE2

        if diff -iBw $TMP_FILE1 $TMP_FILE2 >/dev/null
        then
            echo "$file1 is a copy of $file2"
        fi
    done
done

TMP_FILE1=$(mktemp)
TMP_FILE2=$(mktemp)
trap 'rm -f $TMP_FILE1 $TMP_FILE2' EXIT

# Note the use of sort so line reordering won't prevent detection of plagiarism.

transform() {
    sed '
        s/\/\/.*//
        s/"[^"]"/s/g
        s/[a-zA-Z_][a-zA-Z0-9_]*/v/g
        ' $1|
    sort
}

for file1 in "$@"
do
    for file2 in "$@"
    do
        test "$file1" = "$file2" &&
            break # avoid comparing pairs of assignments twice

        transform "$file1" >$TMP_FILE1
        transform "$file2" >$TMP_FILE2

        if diff -iBw $TMP_FILE1 $TMP_FILE2 >/dev/null
        then
            echo "$file1 is a copy of $file2"
        fi
    done
done
rm -f $TMP_FILE1 $TMP_FILE2

INTERNAL ERROR MISSING FILE: "./templates/topic/shell/code/topic/shell/code/plagiarism_detection.mktemp.sh"

temporary_directory=$(mktemp -d)

# ensure temporary directory + all its contents removed on exit
trap 'rm -rf "$temporary_directory"; exit' INT TERM EXIT

# change working directory to the new temporary directory
cd "$temporary_directory" || exit 1

# we are now in an empty directory
# and create any number of files & directories
# which all will be removed by the trap above

# e.g. create one thousand empty files
seq 1 1000|xargs touch

# print current directory and list files
pwd
ls -l

my_process_id=$$

# launch a asynchronous sub-shell that will kill
# this process in a second
(sleep 1; kill $my_process_id) &

i=0
while true
do
    echo $i
    i=$((i + 1))
done

trap 'echo ha ha' INT

n=0
while true
do
    echo "$n"
    sleep 1
    n=$((n + 1))
done

trap 'echo loop executed $n times in 1 second; exit 0' TERM

# launch a sub-shell that will terminate
# this process in 1 second
my_process_id=$$
(sleep 1; kill $my_process_id) &

n=0
while true
do
    n=$((n + 1))
done

for f in "$@"
do
    clang -c "$f" &
done

# wait for the incremental compiles to finish
# and then compile .o files into single binary
wait
clang -o binary -- *.o

max_processes=$(getconf _NPROCESSORS_ONLN 2>/dev/null) ||
    max_processes=8

# NOTE: this breaks if a filename contains whitespace or quotes

echo "$@"|
xargs --max-procs=$max_processes --max-args=1 clang -c

clang -o binary -- *.o

max_processes=$(getconf _NPROCESSORS_ONLN 2>/dev/null) ||
    max_processes=8

find "$@" -print0|
xargs --max-procs=$max_processes --max-args=1  --null clang -c

clang -o binary -- *.o

parallel clang -c '{}' ::: "$@"

clang -o binary -- *.o