As mentioned in another post, you'll need to run a shell, (whether it be
bash or another system provided shell), in order to process the
commands. If you run the commands directly, there is no shell
interpretation, and the | which passes the output of one command to the
input of the next one won't function as expected,
I don't know what environment processes commands if you run the commands
without a shell environment, it could be FPC, or it could be something
buried in the linux environment, I've never bothered to look up the
answer, but it certainly won't have the redirection capability of the
linux shells provided by the system, and actually, can behave
differently, depending on which shell is used.
You could just add the line:
#!/bin/bash
to the first line of your script, then just call the script from your
program.
Alternatively, you could call the bash command, and pass the command to
it that way, either one should get you the output you desire.
On 5/1/2023 11:00 AM, Bo Berglund via fpc-pascal wrote:
I am trying to create a function to list the available serial ports on a Linux
device. But I have trouble getting commands which work on a terminal to also
work when run from my console program.
When I run this conmmand in the terminal I get the correct reply:
$ ls -l /sys/class/tty/*/device/driver | grep -v "platform/drivers/serial8250" |
awk '{print $9}' | awk -F'/' '{print "/dev/" $5}'
/dev/ttyAMA0
But when I use RunCommand() in FPC it does not work long line wrapped by
newsreader):
program listserialports;
{$mode objfpc}{$H+}
uses
baseunix, classes, sysutils, process;
function ListSerialPorts: integer;
var
ListCmd: TProcessString;
OutData: string;
begin
Result := 0;
ListCmd := 'ls -l /sys/class/tty/*/device/driver | grep -v
"platform/drivers/serial8250" | awk ''{print $9}'' | awk -F''/'' ''{print
"/dev/" $5}''';
Writeln('Command: ' + ListCmd); //To see what is actally sent to Linux
RunCommand(ListCmd, OutData);
Writeln(OutData);
end;
begin
ListSerialPorts;
Writeln('Done');
end.
I see the command being executed but there is an empty output.
If I copy the dislayed command and paste it in and run it I get the result as
shown above. So there should be no typo in the command line, right?
Still no output...
What can I do?
(I have created a shellscript with the same command string and it runs just fine
and prints the data on screen.
But I need the function in order to populate a control with the output inside a
GUI program once thus function works.
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