Questions tagged [fifo]
22 questions
8
votes
3 answers
Read non-blocking from multiple fifos in parallel
I sometimes sit with a bunch of output fifos from programs that run in parallel. I would like to merge these fifos. The naïve solution is:
cat fifo* > output
But this requires the first fifo to complete before reading the first byte from the second…
Ole Tange
- 5,099
7
votes
1 answer
Multiple unix pipes not working
This first pipeline works fine (printing "c"):
echo "a" | sed 's/a/b/' | sed 's/b/c/'
This one does not do what I expect (nothing gets printed when I feed an "a" into my fifo ):
mkfifo fifo;
cat fifo | sed 's/a/b/' | sed 's/b/c/'
However, if I…
Sridhar Sarnobat
- 1,552
7
votes
1 answer
How long do FIFOs (named pipes) stay "open" for?
For example, I have a script that writes the time to a pipe in /etc/pipe. It writes continuously in a while true loop. How long will the data in the pipe be available for reading? If I only decide to read the pipe a day later with cat /etc/pipe,…
nopcorn
- 16,982
6
votes
3 answers
Can bash consume the same fifo from two separate commands?
I have a huge data source that I'm filtering using some greps.
Here's basically what I'm doing right now:
#!/bin/bash
param1='something'
param2='another'
param3='yep'
echo $(avro-read /log/huge_data | grep $param1 | grep "$param2-" | grep $param3 |…
Andrew
- 351
5
votes
2 answers
How to prevent terminating command to send EOF to named pipes?
The problem I faced is exactly this one: http://www.linuxmisc.com/4-linux/d7863c256bccbfb6.htm
I want to be able to run a program which takes stdin, and write data
to it whenever I feel like it. I can do this with fifo named pipes. e.g.:…
justhalf
- 183
5
votes
1 answer
can't scp a named pipe
I am trying to encrypt a file on-the-fly, redirecting the output to a named pipe [fifo]. I SSH into my server and run the command:
$ mcrypt -k key < file > named_pipe
then from my laptop I try to scp it:
$ scp…
Matt
- 787
4
votes
2 answers
Keeping bash open on a named pipe
I'm looking to send commands to a separate tmux pane from vim and I figured the easiest way was to mkfifo a named pipe /tmp/cmds and run bash < /tmp/cmds to listen for commands to run.
I then do echo "echo \"hello world\" > /tmp/cmds" as test, this…
William Casarin
- 1,050
4
votes
2 answers
How can I redirect sound to a FIFO file?
I have a program which uses FIFO files for interacting with the user. An audio call can be made directing the output of arecord to one of the program's FIFO files:
arecord -r 48000 -c 1 -f S16_LE > call_in
An audio call can be answered by directing…
BlandCorporation
- 231
2
votes
1 answer
How to pipe the output of a linux command back into the predecesssing command
The linux command
nc -l 8090 | (read METHOD URI PROTOCOL ; echo "method: $METHOD" ; echo "path: $URI" ; echo "prot: $PROTOCOL")
listens to port 8090 and when I type something like http://127.0.0.1:8090/path/to/nowhere into my browser it prints out…
jederik
- 127
2
votes
1 answer
how to convert a script using pipelines to named pipes
I have a bash script that is using anonymous pipes to achieve:
grabbing video from dv capture device
writing to a file (using tee)
piping it to ffmpeg2theora (converting to ogv/theora video)
writing to a file (using tee)
piping it to oggfwd in…
Luka
- 21
2
votes
1 answer
Shell pipes - the order of things
Because netcat on my box doesn't support -e,
The netcat man page gives me this workaround:
$ rm -f /tmp/f; mkfifo /tmp/f
$ cat /tmp/f | /bin/sh -i 2>&1 | nc -l 127.0.0.1 1234 > /tmp/f
I don't understand how this works.
I though that when you try to…
Drew LeSueur
- 683
2
votes
1 answer
Why does du -sk fail to report the size of a fifo?
There is a concept in bash called process substitution. You can run a command and use the output as a file.
e.g.
$ cat -n <(seq 3|tac)
1 3
2 2
3 1
I am curious why the following fails;
$ du -sk <(xzcat /var/log/mpd/scribble.log.xz…
Ярослав Рахматуллин
- 11,633
2
votes
1 answer
Create STD IN/OUT Buffer for a Program Running in a Screen Session
Environment
Linux version 2.6
Screen version 4.03.01
I am running an application inside of a screen session. The program prints to STDOUT and reads from STDIN.
What I would like to do:
First, have STDOUT of the screen tee'd to a file. For some…
Tim
- 200
2
votes
0 answers
ffmpeg: convert mjpeg fifo into mp4 stream - on the fly- to render in chromium
I have a mjpeg stream in a fifo (comes from gphoto2 --capture-movie) and I want to play that stream in chromium.
To capture the mjpeg stream I use:
gphoto2 --capture-movie --stdout> fifo.mjpg
Now I'm having hard times to figure out how to convert…
pixelbash
- 31
1
vote
1 answer
automatically start netcat on localhost and remote-host and keep it active
I found this answer by @jeremytrimble on Stack Overflow which explains how you can read a FIFO file over network.
I wonder if it’s possible to start these netcat commands automatically, e.g. in a crontab file (@reboot nc …). How would I keep them…
fooness
- 51