Why is the MATLAB startup option '-r' not working properly on C UNIX Shell?

When I run either of the following commands in my C UNIX Shell:

matlab -nojvm -nodisplay -r "ver; quit;" > out.txt &
nohup matlab -nodisplay -nodesktop -nojvm -nosplash -r "ver;quit" > out.txt & 

and issue the command

jobs

I receive the following output which indicates that MATLAB process is suspended:

Suspended (tty output)        matlab -nojvm -nodisplay -r ver; quit; >& out.txt

Answer 1

[MathWorks Support Team]

NOTE: Starting in R2019b, the '-r' option is no longer recommended for non-interactive use. Use the '-batch' option in non-interactive scripting or command line workflows. Do not use this option with the -r option.

This is the expected behavior because when MATLAB has been started without the desktop, it expects to be able to read from standard input ('stdin'), however, when you start it in the background, it cannot read from 'stdin' and the process will be stopped.

As a workaround, you can create a text file which includes the commands you want to execute and use input redirection operator "<" instead of "-r" option. For example, assuming the file "foo.txt" includes the lines

ver;
exit;

you can execute the command

matlab -nodisplay -nodesktop -nojvm -nosplash <foo.txt >out.txt &

As another workaround, you can write a shell script which automates the process.