[Solved]: TProcess in Linux
lazarus / 32-Linux

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gilsonalencar · 2013-10-17 11:43

Hi,

In my Linux application I'm trying to use Tprocess to execute a
specific command line. However, TProcess not recognize  special
characters as “|”. I'm trying to do this:

command:=TProcess.Create(nil);
command.Executable:='dmesg';
command.Parameters.DelimitedText:='| grep tty -i';
command.Execute;

Any sugestion?

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BigChimp · 2013-10-17 11:51

Read the wiki article on executing external processes. TProcess is not
a shell and does not recognize
|
>
<
&
etc.

You can work around it by calling the shell e.g. bash -c ....
something IIRC. See the article.

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gilsonalencar · 2013-10-17 12:19

Works fine in this way:

command:=TProcess.Create(nil);
command.CommandLine:='sh -c "dmesg | grep tty -USB" ';
command.Execute;

But, TProcess.CommandLine is deprecated.

"TProcess is not a shell, so it does not allow i/o redirection,
pipelining, etc."
see this:
http://forum.lazarus.freepascal.org/index.php/topic,13363.msg69804.htm
l#msg69804

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BigChimp · 2013-10-17 12:29

So you should officially use parameters.... in which you can put the
same content... but formatted differently...

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gilsonalencar · 2013-10-17 12:43

Final solution:

command:=TProcess.Create(nil);
command.Executable:='sh';
commnad.Parameters.DelimitedText:='-c "dmesg | grep tty -i" ';
command.Execute;

works fine.

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marcov · 2013-10-17 14:23

Quote from: gilsonalencar on October 17, 2013, 02:43:51 pmFinal
solution:

command:=TProcess.Create(nil);
command.Executable:='sh';
commnad.Parameters.DelimitedText:='-c "dmesg | grep tty -i" ';
command.Execute;

works fine.

But

command.parameters.add('-c');
command.parameters.add('dmesg | grep tty -i');

would be more correct I guess.