Redirecting stdout makes modem unable to connect
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I'm running Yocto with busybox on an embedded system with a Telit modem.
If I launch the main program, script A, with
./script_A &
there's no problem at all and the modem connects on the first try. But when I run
./script_A > /dev/null &
or any other variant to redirect stdout/in/err, the modem cannot connect and shows AT+CSQ=99,99, which means that the signal is not known or not detectable.
Why can't I redirect stdout?
stdout modem pppd
asked Dec 3 at 8:29
William
13
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I'm running Yocto with busybox on an embedded system with a Telit modem.
If I launch the main program, script A, with
./script_A &
there's no problem at all and the modem connects on the first try. But when I run
./script_A > /dev/null &
or any other variant to redirect stdout/in/err, the modem cannot connect and shows AT+CSQ=99,99, which means that the signal is not known or not detectable.
Why can't I redirect stdout?
stdout modem pppd
asked Dec 3 at 8:29
William
13
What is your script doing?
– Kusalananda
Dec 3 at 9:19
@Kusalananda A bunch of GPIO declarations, followed by a while loop:while [ 1 ] do eval killall -HUP pppd eval /path/script_B status=$?I check status to turn off the modem correctly if script B ends for some reason.
– William
Dec 3 at 9:30
add a comment |
up vote
0
down vote
favorite
up vote
0
down vote
favorite
I'm running Yocto with busybox on an embedded system with a Telit modem.
If I launch the main program, script A, with
./script_A &
there's no problem at all and the modem connects on the first try. But when I run
./script_A > /dev/null &
or any other variant to redirect stdout/in/err, the modem cannot connect and shows AT+CSQ=99,99, which means that the signal is not known or not detectable.
Why can't I redirect stdout?
stdout modem pppd
asked Dec 3 at 8:29
William
13
I'm running Yocto with busybox on an embedded system with a Telit modem.
If I launch the main program, script A, with
./script_A &
there's no problem at all and the modem connects on the first try. But when I run
./script_A > /dev/null &
or any other variant to redirect stdout/in/err, the modem cannot connect and shows AT+CSQ=99,99, which means that the signal is not known or not detectable.
Why can't I redirect stdout?
stdout modem pppd
stdout modem pppd
asked Dec 3 at 8:29
William
13
asked Dec 3 at 8:29
William
13
edited Dec 3 at 8:37
asked Dec 3 at 8:29
William
13
asked Dec 3 at 8:29
William
13
asked Dec 3 at 8:29
William
13
13
What is your script doing?
– Kusalananda
Dec 3 at 9:19
@Kusalananda A bunch of GPIO declarations, followed by a while loop:while [ 1 ] do eval killall -HUP pppd eval /path/script_B status=$?I check status to turn off the modem correctly if script B ends for some reason.
– William
Dec 3 at 9:30
add a comment |
What is your script doing?
– Kusalananda
Dec 3 at 9:19
@Kusalananda A bunch of GPIO declarations, followed by a while loop:while [ 1 ] do eval killall -HUP pppd eval /path/script_B status=$?I check status to turn off the modem correctly if script B ends for some reason.
– William
Dec 3 at 9:30
What is your script doing?
– Kusalananda
Dec 3 at 9:19
What is your script doing?
– Kusalananda
Dec 3 at 9:19
@Kusalananda A bunch of GPIO declarations, followed by a while loop:
while [ 1 ] do eval killall -HUP pppd eval /path/script_B status=$? I check status to turn off the modem correctly if script B ends for some reason.– William
Dec 3 at 9:30
@Kusalananda A bunch of GPIO declarations, followed by a while loop:
while [ 1 ] do eval killall -HUP pppd eval /path/script_B status=$? I check status to turn off the modem correctly if script B ends for some reason.– William
Dec 3 at 9:30
add a comment |
1 Answer
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Turns out there was a problem with an AT command for the modem. I needed to send AT+WS46=30 instead of AT+WS46=25.
Talk about a weird side effect.
answered Dec 4 at 8:33
William
13
add a comment |
1 Answer
1
active
oldest
votes
1 Answer
1
active
oldest
votes
active
oldest
votes
active
oldest
votes
up vote
0
down vote
accepted
Turns out there was a problem with an AT command for the modem. I needed to send AT+WS46=30 instead of AT+WS46=25.
Talk about a weird side effect.
answered Dec 4 at 8:33
William
13
add a comment |
up vote
0
down vote
accepted
Turns out there was a problem with an AT command for the modem. I needed to send AT+WS46=30 instead of AT+WS46=25.
Talk about a weird side effect.
answered Dec 4 at 8:33
William
13
add a comment |
up vote
0
down vote
accepted
up vote
0
down vote
accepted
Turns out there was a problem with an AT command for the modem. I needed to send AT+WS46=30 instead of AT+WS46=25.
Talk about a weird side effect.
answered Dec 4 at 8:33
William
13
Turns out there was a problem with an AT command for the modem. I needed to send AT+WS46=30 instead of AT+WS46=25.
Talk about a weird side effect.
answered Dec 4 at 8:33
William
13
answered Dec 4 at 8:33
William
13
answered Dec 4 at 8:33
William
13
answered Dec 4 at 8:33
William
13
13
add a comment |
add a comment |
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What is your script doing?
– Kusalananda
Dec 3 at 9:19
@Kusalananda A bunch of GPIO declarations, followed by a while loop:
while [ 1 ] do eval killall -HUP pppd eval /path/script_B status=$?I check status to turn off the modem correctly if script B ends for some reason.– William
Dec 3 at 9:30