Questions tagged [mkfifo]

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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 ...
Joao Parente's user avatar
6 votes
1 answer
8k views

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 ...
The-null-Pointer-'s user avatar
5 votes
1 answer
4k views

How to check for presence of named pipe on the file system [duplicate]

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 ...
user avatar
4 votes
2 answers
3k views

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 ...
Alexander Mills's user avatar
3 votes
1 answer
9k views

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 ...
Tim's user avatar
  • 101k
3 votes
0 answers
680 views

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 ...
Sinus the Tentacular's user avatar
2 votes
1 answer
2k views

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 <file> | node script.js but the ...
Alexander Mills's user avatar
2 votes
1 answer
1k views

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 ...
sherlock's user avatar
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2 votes
2 answers
56 views

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 ...
Flying Swissman's user avatar
2 votes
1 answer
190 views

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 ...
HollyJolf's user avatar
1 vote
1 answer
822 views

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's user avatar
1 vote
2 answers
157 views

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 ...
fmagno's user avatar
  • 113
1 vote
1 answer
144 views

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 ...
Dzamba's user avatar
  • 11
1 vote
0 answers
191 views

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" | ...
Foo's user avatar
  • 232
1 vote
1 answer
187 views

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/...
steffen's user avatar
  • 121
1 vote
0 answers
174 views

Where should I place named pipe files on RHEL7?

I done some quicky web searches to find out how to make a named pipe. It looks very straight forward I just need to execute as root: mkfifo filename, but what the best practice on where on the ...
Red Cricket's user avatar
  • 2,183
0 votes
1 answer
917 views

Process substitution vs FIFO (created by `makefifo`)

As far as I know, process substitution in bash and FIFO (created by mkfifo) are both named pipes. They both seem viable solutions for communication between processes. I was wondering how to decide ...
Tim's user avatar
  • 101k
0 votes
1 answer
308 views

How to guarantee that that only a specific process reads from a named pipe?

Suppose that, at time (1), I create a named pipe using Python with the goal that eventually this Python process would write something to that named pipe. Why? Because, at time (2), there is another ...
caveman's user avatar
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0 votes
1 answer
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Why don't named pipes respect the order at which readers were attached?

I have this test script: #!/usr/bin/env bash fif="foooz"; rm "$fif" ; mkfifo "$fif" ( cat "$fif" | cat && echo "1") & sleep 0.1 ( cat "$fif" | cat && echo "2") & sleep 0....
Alexander Mills's user avatar
0 votes
1 answer
187 views

Run program when/instead of writing to FIFO? [closed]

I have a program that writes data every second to a FIFO. Now I want to alter some of this data and write it to another FIFO. What would be the best approach? Can I somehow pipe this directly to my ...
TJJ's user avatar
  • 101
0 votes
1 answer
79 views

When does a command in a process substitution or FIFO start and finish running?

When does a command in a process substitution in bash start and finish running? E.g. when does command1 in command2 >(command1) start and finish running respectively? when does command3 in ...
Tim's user avatar
  • 101k
0 votes
0 answers
36 views

Strange incongruent output for both nc and fifo

I have this exact code: #!/bin/bash gtimeout(){ if type -f gtimeout &> /dev/null; then command gtimeout "$@" else timeout "$@" fi } export -f gtimeout; ...
Alexander Mills's user avatar
0 votes
0 answers
59 views

Not able to give input to my telnet connection through fifo file if I run it from script

I have a python script which is sending commands to a fifo file through this command. printf "command" > my1.fifo An another process (telnet login) is taking input from this my1.fifo ...
Anubhav Rai's user avatar
0 votes
1 answer
412 views

Adding 'Progress bar / counter' to a parallelised For Loop

I've been greatly inspired by this question: Parallelize a Bash FOR Loop to parallelise some tools I've written that involve very loooong while read loops (ie doing the same task / set of tasks ...
Owen Morgan's user avatar