Trouble using the system command with special characters

Hi,

I am having trouble using the system command to convert a group of png files (using the wildcard symbol) to a gif using ImageMagick, but within a MATLAB script.

Here is the code that is not working:

datenum = str2num(num);
system('convert −delay 65 −loop 0 [ea,'_',KXXX,'_',datenum(1:end-1),'*_',varplotted,'.png'] [ea,'_',KXXX,'_',datenum,'_',varplotted,'.gif']');

And here is the error when I type just the command in MATLAB interactive mode:

>> 'convert -delay 65 -loop 0 [ea,'_',KXXX,'_',datenum(1:end-1),'*_',varplotted,'.png'] [ea,'_',KXXX,'_',datenum,'_',varplotted,'.gif']'

'convert -delay 65 -loop 0 [ea,'_',KXXX,'_',datenum(1:end-1),'*_',varplotted,'.png'] [ea,'_',KXXX,'_',datenum,'_',varplotted,'.gif']'

|

Error: Invalid text character. Check for unsupported symbol, invisible character, or

pasting of non-ASCII characters.

Thanks!

Answer 1

[Sulaymon Eshkabilov]

One ' sign is missing before 1st comma ","

datenum = str2num(num);
system('convert −delay 65 −loop 0 [ea','_',KXXX,'_',datenum(1:end-1),'*_',varplotted,'.png'] [ea,'_',KXXX,'_',datenum,'_',varplotted,'.gif']');

[KCE]

When I include this, the (new) error message I get is:

Invalid expression. When calling a function or indexing a variable, use parentheses.
Otherwise, check for mismatched delimiters.

Answer 2

[per isakson]

You try to call system() with a sequence of several input arguments and assumes that system() shall join these arguments to the command. system() doesn't work that way.

From the documentation of system

status = system(command) (and click command)

where command should be a scalar string or a character vector.

Thus you need to build ONE character vector (or string scalar), which comprises all parts of the command. Since your command is so long, I propose that you create three variables and finally concatenate them with horzcat().

cmd_1 = 'convert −delay 65 −loop 0 ';
file1 = [ea','_',KXXX,'_',datenum(1:end-1),'*_',varplotted,'.png']; 
file2 = [ea,'_',KXXX,'_',datenum,'_',varplotted,'.gif'];

Before you concatenate them, each one must be a character vector. This code will throw several errors, but it's a beginning.