I once wrote a simple daemon in bash - also sets the values in /proc/*. For example,
echo 50 > /sys/class/backlight/acpi_video0/brightness
I want to rewrite in C + + and share - but how to use the /proc/* in C++? as the client
Remember: on Unix, everything is a file (well, granted, almost everything).
Your current shell code actually means: write the value 50 ( echo 50
) into the file ( redirection operator >
) which name follows ( /sys/class/backlight/acpi_video0/brightness
).
In C++, just open /sys/class/backlight/acpi_video0/brightness
as a file and read/write to it using whatever method you prefer: C++ fstream
, C fopen/fread/fwrite
, ...
Example with fstream
(namely ofstream
since we're only writing to it):
std::ofstream file("/sys/class/backlight/acpi_video0/brightness");
if (!file.is_open())
throw std::runtime_error("Could not open the file");
file << 50;
file.close();
Code sample:
int val = 50;
FILE *f = fopen("/sys/class/backlight/acpi_video0/brightness", "w");
if (!f)
{
fprintf(stderr, "Huh, couldn't open /sys/class ... ");
exit(1);
}
fprintf(f, "%d", val);
fclose(f);
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