Pipes or named pipes are a feature of the POSIX standard that allow separate processes to communicate with each other without having been designed explicitly to work together.

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Piping lines to repeat commands

If my grep operation returns a list of IDs like in the following, can I somehow feed/pipe each line to a commandline command's parameter?: 12345 84758 49549 .. Like for example with the above ...
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17 views

How to pipe arguments into stdin?

I am trying to generate a private key using keytool command, but it asks me for many details like my key passphrase, my name and my organization details. I want to pass all the inputs in one command. ...
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Piping grep causes error $'\302\240grep': command not found on linux

Sometimes when I'm catting & grepping a file, I see this error come up: $ cat something.txt | grep "some text" -bash: $'\302\240grep': command not found When I re-type the command, it works as ...
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842 views

How to find the last match of a string in a bunch of files

I have a bunch of files, I'd like to find the last match of a string in each of them. grep text *.file gives me all the matches not the last ones. ls *.file | xargs grep text | tail -n 1 gives me ...
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17 views

How can I format the piped and refreshing output of multiple cmmands nicely?

I have a command line of multiple piped commands which executes beautifully in bash. For simplification: command1 | command2 | command3 Each command generates output while running, resetting the ...
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1answer
19 views

Detect IPC between running processes on Unix

Suppose I have 2 processes on any unix-based system and I sure they are using some inter-process communication. How can I detect what do they use in order to simulate or hook it? I mean pipes, for ...
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36 views

Batch to retrieve TFS version erroring in FOR /F where TFS attempts to PIPE to findstr

I have this partial batch, but it gives me an error (On 64 bit installations) SETLOCAL EnableDelayedExpansion REM Figure out what ProgramFiles Root we run the command SET ...
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3answers
208 views

Execute command in-between a bash pipe row …?

I want to run a series of piped commands which do a lot of audioprocessing. It looks as follows in pseudocode: command1 | command2 | command3 Of command2 and command3, both take the output of the ...
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3answers
70 views

real windows equivalent to cat *stdin*

Under cmd is there a windows equivalent to the posix command cat ? cat all by itself no filenames, no switches. I just want something that copies stdin to stdout until it hits EOF. it's not a hard ...
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40 views

How can I use the pipeline output from different commands inside a custom bash script?

I have this simple script: #!/bin/bash # This command removes the last "\n" (line feed) character from the file specified as parameter # # Params: # $1 [FILE_NAME] - the name of the file to trim if ...
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2answers
42 views

How to save console output still showing it

I need to troubleshoot a telnet session and send save it's results to another person. When I use redirection I save the contents of my session, but I'm not able to see it on console. How to pipe ...
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Rendering HTML from a pipe

I would like to be able to generate HTML then pipe it to a program which will render it, something like this: for i in 1 2 3 do for j in a b c do echo "<table ...
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5answers
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How can I save the current contents of less to a file?

If I've piped the results of a command to less and then decided that I want to save the contents to a file, is this possible? I've tried setting a mark a at the end of the buffer, and then returning ...
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1answer
15 views

pv: Change Prefix on the Fly

To me pv is really handy some times. However, I was wondering if it was possible to change the prefix on the fly. I mean usually I have something like in.sh | pv -btrcN "Watch that work!!1!" | ...
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1answer
52 views

Passing the output of locate as an argument to an editor

What I mean is doing this in a 1-liner: ubu@ubuntu:~$ locate filename.sh /home/ubu/path/to/filename.sh ubu@ubuntu:~$ gedit /home/ubu/path/to/filename.sh I can't seem to figure out the right piping ...
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1answer
51 views

redirect a file generated by a program to another program

In linux enviroment, I have a program that creates a large file (2-3GB). I need to filter this file (e.g. I want to remove a line if it appears in the precedeing 10 lines). I want to do it while the ...
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1answer
61 views

How to split and recombine stdout pipe in bash?

I am parsing text on the command line. How can I take the output of one command and use it in two places in the next command? some_command | head -n $( awk '/search_term/ {print FNR} ...
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1answer
14 views

Is it possible to count from a given number when extracting images from a video with FFmpeg?

I am using ffmpeg to extract still images from a video. First from the beginning of the video, to a given time and then from the end of the video from a given time. So I am using two ffmpeg command ...
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1answer
34 views

Pipe standard error to file and keep it on standard error?

I have a script (fragment) for which I'm logging output and standard error: #!/bin/sh #... { date "+%Y-%m-%d %T" cd $workdir ls -ltr validfile badfile #example command that provides stdout, ...
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0answers
105 views

Pipe ffmpeg->ffmbc cut files after some length

I recently tried the following command: ffmpeg.exe -i "C:\Users\Dennis\git\cnn\CNN\watch\filea.mp4" -i "C:\Users\Dennis\git\cnn\CNN\watch\fileb.mp4" -filter_complex ...
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2answers
404 views

How to unrar the STDIN?

What I have tried: cat archive.rar | unrar x - cat archive.rar | unrar x /dev/stdin cat archive.rar | 7z x - cat archive.rar | 7z x -si cat archive.rar | 7z l -si The unrar doesn't recognise the - ...
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42 views

Win7 Command Line piping

I want to know why in the command line prompt this happens. I have a script fileX.cmd which is one single line of text: @echo dir If I do C:\Users\Dogfood>fileX.cmd | cmd This will show all ...
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53 views

Ping piped to txt does output nothing

Following script should pipe the ping output to a text file @echo off rem end with ctrl+c y ping 192.168.33.65 -t >> C:\_ScriptLog\Ping\ping.txt but nothing is piped to the txt file, it´s ...
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How to rate-limit a pipe under linux?

Is there a filter which I could use to rate-limit a pipe on linux? If this exists, let call it rate-limit, I want to be able to type in a terminal something like cat /dev/urandom | rate-limit 3 -k | ...
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How do I output a variable without changing if it has a newline or not in a shell script?

I have a shell script that takes input from another shell script. The stream gets piped in on stdin. I need to capture all the bytes of the stdin stream to a single variable in the shell script. ...
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4answers
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How to redirect the output of a program to the Linux diff command

I have a program that writes to stdout. Is there a way that I can redirect the output to the Linux diff command or do I have to write the output to a file and then compare that? For example, I have a ...
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cURL: how to suppress strange output when redirecting?

I'm trying to print just the verbose sections of a cURL request (which are sent to stderr) from the bash shell. But when I redirect stdout like this: curl -v http://somehost/somepage > /dev/null ...
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13 views

Merge two outputs into one in real time without scrambling them in linux

Is it possible to merge two real time outputs into one file without scrambling the new lines? What I want to do is something like cat <(/proc/kmsg) <(while true; do echo hello; sleep 1; done) ...
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1answer
106 views

How to parse pipe with multiple commands independently?

How can I parse output of a single command by multiple commands without truncating at each step? For example ls -al|grep -i something will pass every line that has "something" in it to the next ...
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38 views

Trying to cat the result of piped commands

I have a folder of files that are named list20140801.txt list20140802.txt .... I'm trying to do this ls | sort | tail -3 | cat But it is just giving me the file names, not cat'ing them.
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How to get both PIPESTATUS and output in bash script

I'm trying to get last modification date of a file with this command TM_LOCAL=`ls -l --time-style=long-iso ~/.vimrc | awk '{ print $6" "$7 }'` TM_LOCAL has value like "2012-05-16 23:18" after ...
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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 ...
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6answers
1k views

How can I both pipe and display output in Windows' command line?

I have a process I need to run within a batch file. This process produces some output. I need to both display this output to the screen and send (pipe) it to another program. The bash method uses ...
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3answers
82 views

Pass stdin to multiple programs without closing

I want to split and GZip a large file, and this answer appeared to be what I'm looking for, and it seemed like a very useful way of doing things I never thought of, so I'd like to generalize it; the ...
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1answer
182 views

How to shuffle large text files efficiently while piping it on Linux?

I have a text file that is couple GBs. I am trying to shuffle this text file in a pipe. For example these are some sample lines of what I am using but it is not efficient and in fact the pipe does ...
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3answers
5k views

Silence curl with >/dev/null 2>&1 when it's piped

So I have a curl that is piped to a grep and a sed. Where would I apply the >/dev/null 2>&1 ? curl www.site.com | grep stuff | sed "other stuff" At the very end or after the curl?
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how to beep on tail -f event

I want my PC to make a system beep on every tail event I have the following command tail -f development.log | grep "something rare" is there an easy way like pipeing it to somthing that beeps? ...
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52 views

Multiple grep command and show after line

I have this command grep -iE -A18 "$(date +"%Y-%m-%d").*error" * | grep -v -A18 'Movig to Error Queue' but the result shows me the 18 line after 'Moving to Error Queue' but I do not want that. I ...
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6answers
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What is the general consensus on “Useless use of cat”?

When I pipe multiple unix commands such as grep, sed, tr etc. I tend to specify the input file that is being processed using cat. So something like cat file | grep ... | awk ... | sed ... . But ...
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3answers
4k views

How to pipe awk output (with periodic, continuous input) to output file?

I am trying to write a command that pipes the continuous output of a free command (run every second) to an awk command that parses a specific value (available free memory) and outputs this to a file ...
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1answer
75 views

Linux - Output to Folder that Yet Exists (in one command)

Is it possible to achieve this in one command without requiring a script: echo "test" > /folder/that/does/not/exist/newFile.txt
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1answer
205 views

Use 'find' command to search for PNG files, pipe output to imagemagick for batch conversion

I've got a directory with thousands of image files, mostly JPG but some PNG. The files have no extension, they're just numbered. I need to convert all of them to JPG. Using find I can get a list of ...
3
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1answer
92 views

Using pv(1) to limit rsync speed

I'm trying to use pv rather than rsync's builtin --bwlimit to limit the bandwidth of an rsync transfer because --bwlimit is implemented in an eventually-consistent way, and my transfers are so short ...
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Why is piping 'dd' through gzip so much faster than a direct copy?

I wanted to backup a path from a computer in my network to another computer in the same network over a 100 Mbit/s line. For this I did dd if=/local/path ...
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55 views

Use grep to find files and pipe/open to open them

How can I pipe files from grep to open all matching files? I've tried grep -li "type" * | open, but that does not work.
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525 views

How to a open a file in vim using pipe

I get to use the locate command extremely often. So if I run the following command. locate updatedb | head -1 Then it gives me the O/p /usr/updatedb.conf I wonder if there is any such command ...
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Advantages of cat'ing file and piping to grep

Are there any additional advantages of cat'ing a file and piping it to grep, besides convenience? The convenience being that, when I retrieve commands such as those below from my history, the cursor ...
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3answers
244 views

With regards to piping commands, what are the greater than (>) and less than (<) symbols called?

On linux at least, and I think windows/dos shell too you can use > to "pipe" output into a file. Something like: cat myfile.txt > mightAsWellCP.txt What is that piece of syntax sugar called? ...
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3answers
10k views

Passing two arguments to a command using pipes

Usually, we only need to pass one argument: echo abc | cat echo abc | cat some_file - echo abc | cat - some_file Is there a way to pass two arguments? Something like {echo abc , echo xyz} | cat ...
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What does the linux pipe symbol “|” do? [duplicate]

Here is a command that sorts files in a folder in reverse order ls | sort -r What does the | symbol in that command do? What I'm really looking for here is high level (easy to understand) ...