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Full Discussion: Writing to a Serial Port
Top Forums Web Development Writing to a Serial Port Post 302921695 by neutronscott on Sunday 19th of October 2014 05:31:12 PM
Old 10-19-2014
This is not reading from the port. You cannot do 2 redirections. You're attaching stdout to /dev/ttyS0 but immediately changing that to a file called bla.

Code:
mute@thedoctor:~$ echo hi >file1 >file2
mute@thedoctor:~$ ls -l file?
-rw-r--r-- 1 mute mute 0 Oct 19 21:29 file1
-rw-r--r-- 1 mute mute 3 Oct 19 21:29 file2

This shows how redirection to two places fails. You only need to:
Code:
$ echo W >/dev/ttyS0
$ cat /dev/ttyS0

Try to set permissions, as root, to allow everyone access to the serial port with chmod 0666 /dev/ttyS0. If your code then works, the issue is that the webserver doesn't run as ethan, but another user who doesn't have access to ttyS0.
 

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MIXERCTL(1)						    BSD General Commands Manual 					       MIXERCTL(1)

NAME
mixerctl -- control audio mixing SYNOPSIS
mixerctl [-d file] [-n] [-v] -a mixerctl [-d file] [-n] [-v] name ... mixerctl [-d file] [-n] -w name=value ... mixerctl [-d file] [-n] -w name++ ... mixerctl [-d file] [-n] -w name-- ... mixerctl [-d file] [-n] -w name+=value ... mixerctl [-d file] [-n] -w name-=value ... DESCRIPTION
The mixerctl command displays or sets various audio system mixing variables. If a list of variables is present on the command line, then mixerctl prints the current value of those variables for the specified device. If the -a flag is specified, all variables for the device are printed. If the -w flag is specified, mixerctl attempts to set the specified variables to the given values. The -d flag can be used to give an alternative mixer device. The default is /dev/mixer. The -n flag suppresses printing of the variable name. The -v flag shows the possible values of enumeration and set valued variables. Enumerated values are shown in brackets (``[]'') and set val- ues are shown in curly braces (``{}''). The exact set of controls that can be manipulated depends on the mixer. The general format (in both getting and setting a value) is class.name = value class can have values like inputs or outputs, indicating that the control affects the input or output of the mixer, respectively. name indi- cates what part of the mixer the control affects. Continuous mixer values, e.g., volume, have numeric values in the range 0-255. If value can be set for each channel independently, the values are printed separated by commas. Discrete mixer values, e.g., the recording source, have symbolic names. Depending on the mixer it may either be an enumeration or a set. The suffixes ++ and -- can be used to step through the values of a mixer control. For numeric controls, these operators increase or decrease, respectively, the value by an amount (the delta) suitable to make the control assume the next possible value. For binary controls, these operators toggle between on and off. The operators += and -= change the value of a mixer control by the indicated number of steps. ENVIRONMENT
MIXERDEVICE the mixer device to use. FILES
/dev/mixer mixer audio device /etc/mixerctl.conf mixer configuration file EXAMPLES
The command mixerctl -a -v can produce inputs.mic=0,0 volume inputs.mic.mute=off [ off on ] inputs.cd=220,220 volume inputs.cd.mute=off [ off on ] inputs.dac=220,220 volume inputs.dac.mute=off [ off on ] record.record=220,220 volume record.record.source=mic [ mic cd dac ] monitor.monitor=0 volume COMPATIBILITY
The old -f flag is still supported. This support will be removed eventually. SEE ALSO
audioctl(1), audio(4), mixerctl.conf(5), sysctl(8) HISTORY
The mixerctl command first appeared in NetBSD 1.3. BSD
August 15, 2008 BSD
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