A Unix pipe connects file descriptors of two processes. A pipe is created with the POSIX pipe() function declared in . Shells provide pipe creation between processes using "|".

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piping with grep

I want to search "C" in the grades column inside the file "input.csv": roll,name,total,rank,grade 001,A B,78,23,C 003,F YZ,100,1,* and what I'm trying is: cut -d"," -f4 input.csv | grep "C" ...
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2answers
103 views

Merge lines in file together from regex to “lineify” multiline log log files

Stadard unix command line tools (grep, cut, sed etc.) all work one line at a time. And nearly always, this is great. However I am trying to parse some postgresql slow query logs. Each entry has some ...
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2answers
58 views

Using a file as an input to a script

Say I want to use the name of a file as input, and process it with a pre-made script in a certain directory. How do I do it? fileName < /folder1/scriptName is this the right format?
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1answer
457 views

pipe mplayer output to other tool

I'm trying to play an online live stream via mplayer and pipe the audio from that stream to another tool. Playing the stream works fine: mplayer http://user:pass@192.168.0.1:8080/stream.flv But ...
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1answer
70 views

pipe speed benchmark with machine readable output

I'm looking for a tool similar to pv which is producing machine readable output. And i cant believe that nobody did it bevore... I looked at the manpages of pv, pipemeter, dd and cpipe but all these ...
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1answer
125 views

Is there a system call to bind a file descriptor directly into another?

A read() & write() loop would probably be as good as what I'm looking for, but nevertheless is anything like that around or is it impossible because of an obstacle I didn't envisage ? I'm curious
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1answer
89 views

Grep -v filter not working

I want to filter grep results by using grep -v option. But the output does not differ when using a particular pattern. contents of log.log: ERROR error EXCEPTION exception ...
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1answer
47 views

Fetch second and fourth column from a file

Problem Statement I am not able to get the values in second and fourth column. Tried grep -i "AUGC\|AACN\|AACY" output.csv | cut -d ',' 2,4 DATA ...
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127 views

Combine the output of while loop into tar

I'm trying to create a script that mysqldumps all my databases, creating an individual .sql file for each database and combines the output into backup-DATE.tar.gz. I've gotten as far as being able to ...
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1answer
344 views

Redirect a directory as input to a script and output to a file

I want to use a directory name as a parameter for a pre-made script. Then the output goes into a newly made file in the home directory. It involves pipe/redirection. How do I do that? read dir $dir ...
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Scripted write-then-read from Unix domain socket using socat

I have a simple server listening on a Unix domain socket (on a CentOS box in case that's important). When I send the command "DATE" to the socket it writes back a welcome message and then "APRIL 15 ...
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0answers
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Understanding inotifywait, pipes and buffers

I want to monitor every file change in a directory with inotifywait. inotifywait shall write to a FIFO buffer, which then can be read, leisurely. While experimenting with relatively huge amounts of ...
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0answers
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How many ways are there to convert and pass stdin as command parameter?

I am new to Linux shell. I know that xargs can be used to accept stdin from a pipe and pass it to another command as parameter. Are there other ways to do so? Is there a list I can refer to? A ...
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0answers
123 views

Pipe a .BIN file into XModem transfer

I need to send a .bin file to a modem via XModem transfer for firmware upgrading. If the modem is connected to a local computer, the command would be the following: sz -X -k -b -vvv - ...
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0answers
46 views

Close All Piped Commands if one close

I'm running at least 3 commands (with progs) using pipes. For example program1 bla bla | program2 blabla | program3 bla bla Is possible to close all programX PIDS automatically if at least one ...
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0answers
506 views

avconv/ffmpeg output through /dev/ttyAMA0

I tried to pipe streaming video from video4linux2 webcam connected to a Raspberry Pi through /dev/ttyAMA0 to a computer using an Arduino as a intermediary. First of all, is it possible? Because I was ...
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0answers
538 views

How to redirect and use the framebuffer?

I need to work on the framebuffer to record what is being rendered. Now, I figure out how to convert the framebuffer in an image, I'm currently unable to obtain a constant stream of data from the fb ...
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0answers
201 views

Automatically start named pipe reader on startup?

I'm trying to run a script with root access from PHP. I can't do that because Apache's user, www-data, don't have root access because of security reasons. To fix that, I was advised to use a named ...
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21 views

Pipe output of process that's already running

I've got a process that spews out a lot of output, and it's going to be running for the next hour. I forgot to pipe its output through my awk script before I started running it. Now my terminal is ...
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20 views

Half-close netcat connection

How can I have a netcat connection terminate the sending half of a TCP connection if its input reaches EOF? I have a (non-standard) TCP service which reads all its input (i.e. until the client sends ...
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0answers
79 views

csh: redirecting output from foreach

In csh: How do I redirect the output from a foreach-loop to a pipe? This works but uses a temp file: set tmpfile=/tmp/file ...
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0answers
37 views

UDEV-rule:Open new gnome-terminal window on usb-plugin AND activate it for stdin/stdout/stderr?

My attempt is this: If a certain USB-device is plugged in, I want to open a gnome-terminal window in my desktop-environment. This newly opened window must be able to be interactive, this means, the ...
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0answers
21 views

Pipe gzip output to Bluetooth transfer?

How do I pipe gzip output to Bluetooth transfer? I am able to send send file over Bluetooth using this command: bluetooth-sendto --device=12:23:35:96:45:45 file.tar However, piping gzip didn't ...
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Correct/Efficient/Reliable way to import log file entries to a MySQL database?

I'd like to be able to query our server access log files to identify abuse patterns. Log files really aren't very queryable, and it would be fairly easy to do what I wanted if each hit was a row in a ...
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0answers
112 views

Verbose output in logfile and simple output on screen?

Let's say I have the following script: script.sh and i want the verbose output in a logfile and simple output on screen. Logfile should contain the csh -v script.sh output, and on the screen should ...
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445 views

Why does this pipeline get SIGTTIN?

When I run the command for i in *.log; do cat "$i" | sort; done | more, the pipeline gets a SIGTTIN signal and is stopped. bash$ for i in *.log; do cat "$i" | sort; done | more ### (one screenful of ...
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“yes | head” never stops when executed from Apache server?

I have a page on my site that runs a script that involves yes. The line that invokes yes is like this: fullalistan="$(yes "$firstnopng" | head -n $repeater | awk '{ print $0 "" FNR ".png" }')" Now ...
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Piped sequence - printing

I need to write a piped sequence of commands that prints out a list of all sub directories of a current directory. In order to get all sub directories of a current directory I use: ls -D Since I am ...