I've recently found here a solution to my problem, but I can't completely understand what everything in this command means:
xdg-open "$@">/dev/null 2>&1
"$@" is equivalent to
"$1" "$2" ... (the positional parameters to the command, good to use when there are special characters, for example spaces, within the parameters).
Special Parameters The shell treats several parameters specially. These parameters may only be referenced; assignment to them is not allowed. * Expands to the positional parameters, starting from one. When the expansion is not within double quotes, each positional parameter expands to a separate word. In contexts where it is performed, those words are subject to further word splitting and pathname expansion. When the expansion occurs within double quotes, it expands to a single word with the value of each parameter separated by the first character of the IFS special variable. That is, "$*" is equivalent to "$1c$2c...", where c is the first character of the value of the IFS variable. If IFS is unset, the parameters are separated by spaces. If IFS is null, the parameters are joined without intervening separators. @ Expands to the positional parameters, starting from one. When the expansion occurs within double quotes, each parameter expands to a separate word. That is, "$@" is equivalent to "$1" "$2" ... If the double-quoted expansion occurs within a word, the expansion of the first parameter is joined with the beginning part of the origi‐ nal word, and the expansion of the last parameter is joined with the last part of the original word. When there are no positional parameters, "$@" and $@ expand to nothing (i.e., they are removed).
Redirection of standard output to a file
The special file that means that the output will be redirected 'nowhere' in other words not written anywhere.
man null for more details.
Redirection of error output to a file
Redirection of error output to standard output
Note that the order of redirections is significant. For example, the com‐ mand ls > dirlist 2>&1 directs both standard output and standard error to the file dirlist, while the command ls 2>&1 > dirlist directs only the standard output to file dirlist, because the standard error was duplicated from the standard output before the standard output was redirected to dirlist.