test1=`sed -i "/:@/c connection.url=jdbc:oracle:thin:@$ip:1521:$dataBase" $search`
valid $test1

function valid () {
  if $test -eq 1; then
    echo "OK"
    else echo "ERROR"
  fi
}

some_command
if [ $? -eq 0 ]; then
    echo OK
else
    echo FAIL
fi

some_command
retval=$?
do_something $retval
if [ $retval -ne 0 ]; then
    echo "Return code was not zero but $retval"
fi

if some_command; then
    printf 'some_command succeededn'
else
    printf 'some_command failedn'
fi

if output=$(some_command); then
    printf 'some_command succeded, the output was «%s»n' "$output"
fi

command && echo OK || echo Failed

cd /nonexistant
if [ $? -ne 0 ]
then
    echo failed
else
    echo success!
fi

command && echo $? || echo $?

$ find . -name "not_existing_file"
$ echo $?
0
$ file ./not_existing_file
./not_existing_file: cannot open `./not_existing_file' (No such file or directory)
$ echo $?
0

$ file ./doesntexist  | while IFS= read -r output; do
> case "$output" in
> *"No such file or directory"*) printf "%sn" "This will show up if failed";;
> *) printf "%sn" "This will show up if succeeded" ;;
> esac
> done
This will show up if failed

$ find . -name "doesn'texist" | if ! read IFS= out; then echo "File not found"; fi
File not found

error="$([COMMAND] $1 2>&1 >/dev/null)"

if [ $? -ne 0 ]; then
    echo "[THIS-FUNCTION]: $error"
    exit 1
fi