Questions tagged [pipe]
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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Getting colored results when using a pipe from grep to less
I use the --colour option of grep a lot, but I often use less as well. How can I pipe grep results to less and still preserve the coloring. (Or is that possible?)
grep "search-string" -R * --colour | ...
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Preserve colors while piping to tee
ls -l --color=auto | tee output.log
Without pipe/tee it's colored. How can I make it so that it stays colored while using tee (can be colored only on the screen, I don't care about colors in logs).
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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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How to pipe command output to other commands?
Example:
ls | echo prints nothing ( a blank line, actually ). I'd expect it to print a list of files.
ls | grep 'foo', on the other hand, works as expected ( prints files with 'foo' in their name ).
...
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How to suppress cUrl's progress meter when redirecting the output?
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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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 of=/remote/path/in/local/network/backup....
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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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Can I use pipe output as a shell script argument?
Suppose I have a bash shell script called Myscript.sh that need one argument as input.
But I want the content of the text file called text.txt to be that argument.
I have tried this but it does not ...
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Why does Powershell silently convert a string array with one item to a string
Consider the following Powershell script, which searches for folders in C:\ with a 'og' in their name:
PS C:\> (ls | %{$_.Name} | ?{$_.Contains("og")})
PerfLogs
Program Files
setup.log
Now I narrow ...
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Bash: create anonymous fifo
We all know mkfifo and pipelines. The first one creates a named pipe, thus one has to select a name, most likely with mktemp and later remember to unlink. The other creates an anonymous pipe, no ...
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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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Is there any way to keep text passed to head, tail, less, etc. to be colored?
Is there any way to keep colorization of text passed through pipe | to head, tail, less, etc.?
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Pipe to less but keep the highlighting
Is it possible to pipe output (e.g. dmesg) to a command like less (or equivalent) and keep the text highlighting used by the original command?
example: on the left dmesg | less on the right dmesg
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Find what process is on the other end of a pipe
I'm trying to trace some odd behavior of a few processes and ran into a point I'm not sure how to trace past. The hung process, which I attached to using strace -p showed this:
Process 7926 attached ...
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Comments in a multi-line bash command
This single-command BASH script file is difficult to understand, so I want to write a comment for each of the actions:
echo 'foo' \
| sed 's/d/a/' \
| sed 's/e/b/' \
| sed 's/f/c/' \
> myfile
...
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Howto pipe: cp | tar | gzip without creating intermediary files?
Can anyone tell me if it's possible to pipe | this without having to create a physical file anywhere between A and B.tar.gz?
This is what I'm trying to do:
File A
Rename A to B
Tar B.tar
gzip -9 B....
regan
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How can I pipe output of ffmpeg to ffplay?
How can I pipe the output of ffmpeg to ffplay?
At the moment I use a workaround in bash :
mkfifo spam
(ffplay spam 2> /dev/null &) ; capture /dev/stdout | ffmpeg -i - spam
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how to escape pipe symbol | in bat scripts?
I need to echo commad usage like this in batch script named command.bat
command.bat on|off
I cant use
echo %0 on|off
I know I can use
echo "%0 on|off"
but it puts quotes along
Is there any ...
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Why is xargs necessary?
Suppose I want to remove all files in a directory except for one named "notes.txt". I would do this with the pipeline, ls | grep -v "notes.txt" | xargs rm. Why do I need xargs if the output of the ...
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Downloading Youtube videos in a text file...?
If you are familiar to Linux, see the following script...
I have a text file with a (list.txt) of Youtube URLs separated by new line... and I use
cat list.txt | youtube-dl -f best
to download all ...
user720745
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Using -replace on pipes in powershell
I want to test out a replace before I use it, so I'm trying to write a quick online command to see what the output is. However, I'm not sure what the syntax is. What I want to do is something like
...
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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
cat ...
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Pipe gunzip and mysql to gunzip a dump and import it
I have a .gz sql dump file (example: foo.sql.gz) that i want import in my database with the classic mysql command.
gunzip -c foo.sql.gz > foo.sql
mysql -uroot -ppassword foo < foo.sql
foo is ...
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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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Make a pipe conditional on non-empty return
Is there a way to pipe the output of one function to another, but only if there is an output?
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How do I pipe output to date -d "value"?
I have a date like 2014-01-30 05:04:27 GMT, and if I run date -d "2014-01-30 05:04:27 GMT", the output is in my server's timezone (Thu Jan 30 16:04:27 EST 2014).
With the use of grep and cut,...
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What does the last "-" (hyphen) mean in options of `bash`?
In this tutorial we need to execute the following command:
# curl -sL https://rpm.nodesource.com/setup_6.x | sudo -E bash -
What does the last - (hyphen) after bash mean?
I've seen a lot of ...
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Setting pipefail for a single piped command
I need to execute a number of piped shell commands from a non-BASH script (namely PHP script) like these:
command1 | command2 | command3
so that, if command1 fails with a non-zero exit code, each ...
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In windows, can I redirect stdout to a (named) pipe in command line?
Is there a way to redirect the standard output of a process in Win32 console to a named pipe?
Named pipes are built in to Windows and while they would be an useful concept, I've never seen them used ...
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Why does this not work? "ls *.txt | xargs cat > all.txt" (all files into single txt document)
Why does this not work?
ls *.txt | xargs cat > all.txt
(I want to join the contents of all text files into a single 'all.txt' file.)
find with -exec should also work, but I would really like to ...
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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) ...
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What is the magic separator between filenames in ls output?
The output of ls (with no arguments) appears to separate filenames with linebreaks.
Evidence:
ls | grep foo works as expected, with grep treating each filename as a separate line of input.
ls > ...
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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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Windows how to redirect file parameter to stdout? (Windows equivalent of `/dev/stdout`)
Windows console:
Tool A can write binary data to a file, but has no option for telling it to use stdout.
Tool B can read binary data from stdin and process the info in it.
How can I get the output ...
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pipe and stdin redirection to cat
Why does
echo "hello world" | cat
works while
cat < echo "hello world"
does not? My (incorrect) intuition is that pipe would redirect stdout to cat as stdin.
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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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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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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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Get response body and show HTTP code by curl
I have endpoint which returns JSON (response body). I need get by curl the response body and process it (for example using jq). It works:
response=$(curl -s https://swapi.dev/api/people/1?format=json)
...
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Netcat/socat behavior with piping and UDP?
I guess this is close to linux - Netcat stops listening for UDP traffic - Super User, but I thought I'd better ask anyways
As far as versions of netcat I'm using Ubuntu 11.04 and the default netcat ...
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What does "2>&1" do when posted BEFORE 1>x?
I know what this command does:
command 1>/dev/null 2>&1
But what, if anything, does the following do?
command 2>&1 1>/dev/null
I still see standard error output with the second ...
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Is pipe ( | ) a command?
As I understand it, pipe ( | ) takes the standard output of one process and passes it as standard input into another process.
But I want to know if pipe ( | ) is considered a command like ls, grep ...
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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 border="1"><tr&...
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What are reasons for local Windows named-pipes to fail?
I've been working hard on this one all day and I'm stuck. This morning our asian collegues called me because a SolidWorks addin for our product data management system could not communicate with the ...
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Pipe file content into PowerShell command without loading the entire file to memory
I've recently started using PowerShell, hoping to never miss Bash again.
I want to restore an instance of a PostgreSQL database. In Bash, or in the old command prompt, I would type:
psql --...
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Is backwards redirection the same as a pipe?
In Linux if you type
sort < txtfile
is that the same thing as
cat txtfile | sort
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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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How to pipeline stderr in cmd.exe?
Some programs would prefer to output the help message in stderr. I want to search the help message with grep command, xx /? | grep regex?
How could i do this?
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Does pipe have to write temporary file?
I found that if I transfer a great amount of data between two processes via pipe, some temporary file will be created by linux in /tmp directory. If the pipe operation succeeds, the corresponding ...
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I would like to pipe output of find into input list of scp, how?
I'm a novice linux user and I am trying to send a long list of files from one computer to another. The argument list is too long, so I am using find. I am having trouble setting up the expression, ...
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