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Questions tagged [mkfifo]

23 questions
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Why doesn't mkfifo with a mode of 1755 grant read permissions and sticky bit to the user?

I'm creating a server and client situation where i want to create a pipe so they can communicate. I created the pipe in the server code with mkfifo("fifo",1755);: 1 for only user that created and root to be able to delete it or rename it, 7 for…
Joao Parente
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1 answer

How does this command work? mkfifo /tmp/f; cat /tmp/f | /bin/sh -i 2>&1 | nc -l 1234 > /tmp/f

Today I was reading the nc man page and stumbled on this command. I know that: mkfifo /tmp/f is creating a named pipe at /tmp/f. cat /tmp/f is printing whatever is written to that named pipe and the output of cat /tmp/f is been piped to…
The-null-Pointer-
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How to check for presence of named pipe on the file system

I tried using the -f flag to test if a named pipe is present if [[ ! -f "$fifo" ]]; then echo 'There should be a fifo.lock file in the dir.' > /dev/stderr return 0; fi this check does not seem correct. So perhaps a named-pipe is not a file, but…
user282164
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How to pipe all output streams to another process?

Take the following Bash script 3-output-writer.sh: echo A >&1 echo B >&2 echo C >&3 Of course when ran as . 3-output-writer.sh it gets the error 3: Bad file descriptor, because Bash doesn't know what to do with the 3rd output stream. One can easily…
Sinus the Tentacular
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How to write something to named pipe even if there are no readers

I have this little test script: rm fooo | cat mkfifo fooo echo 'bar' > fooo # blocks here echo 'done' I am guessing that because there is nobody reading from the named pipe, that the write call will block until then. Is there some way to write…
Alexander Mills
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What is the purpose of using a FIFO vs a temporary file or a pipe?

From APUE FIFOs can be used to duplicate an output stream in a series of shell commands. This prevents writing the data to an intermediate disk file (similar to using pipes to avoid intermediate disk files). But whereas pipes can be used …
Tim
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Process in Pipe which Processes 256 bytes at a Time

I have a c program on a Cyclone 5 that does an FFT using the connected FPGA. This program currently takes 256 bytes from stdin and then process it gives the FFT results on stdout. I run it like this from the Linux bash on the Cyclone 5. ./fpga_fft <…
Flying Swissman
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Using tee and paste results in a deadlock

I am trying to redirect stdout of a command into two "branches" using tee for separate processing. Finally I need to merge results of both "branches" using paste. I came up with the following code for the producer: mkfifo a.fifo b.fifo python -c…
HollyJolf
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How to create a bidirectional pipe in bash?

I have a program which reads from and writes to file descriptor 3. I want to let it write to fd 3, and be able to write to the other end of the pipe interactively which the program should read over the same fd. I can create a pipe with mkfifo…
sherlock
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pipe data into process that's already started

Say I start a node.js process like so: node script.js & is there a way to pipe data into that process after it has started? normally, we do this: cat | node script.js but the problem I am seeing is that sometimes the node.js process won't…
Alexander Mills
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Unable to redirect stdout for background terraform process after it received input from named pipe

I have a terraform file: terraform { required_version = "1.3.5" } locals { a = "foo" b = "bar" } in a bash terminal, I can do: $ echo "local.a" | terraform console "foo" $ echo "local.b" | terraform console "bar" Now what I'm trying to do…
Foo
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Speed up grep usage inside bash script

I am currently working on creating a bash script that is supposed to process large log files from one of my programs. When I first started the script took around 15 seconds to complete which wasn't bad but I wanted to improve it. I implemented a…
Dzamba
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Process (mplayer) doesn't read from named pipe when started from webserver (lighttpd)

tl;dr $ sudo -u www-data mplayer -slave -input file=/srv/mplayer.fifo -playlist /srv/list & $ lsof /srv/mplayer.fifo | tail +2 mplayer 21059 www-data 4u FIFO 179,2 0t0 2359331 /srv/mplayer.fifo $ cat…
steffen
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mkfifo to copy / move files

Is it possible to use mkfifo (named pipes) in Linux to copy files? For example: I am extracting files from tar archive and I want them to be moved immediately to another location.
micholeodon
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Two named PIPEs (PIPE_in/PIPE_out) connected with `tail -f` | String sent to PIPE_in doesn't reach PIPE_out

1.Create named PIPEs, pipe_in and pipe_out by running: $ mkfifo pipe_in $ mkfifo pipe_out 2.Connect pipe_in to pipe_out: TERM0: $ tail -f pipe_in > pipe_out 3.Send string hello world! to pipe_in and expect it to arrive at pipe_out: TERM1: $ tail…
fmagno
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