Linked Questions
21 questions linked to/from How can I send stdout to multiple commands?
1
vote
3
answers
2k
views
Pipe output of one command to two others [duplicate]
I need to pipe the output of one command to two other commands.
cat filename.txt | tail -n 1
cat filename.txt | wc -l
Since the file is huge I want to avoid reading it twice. I checked tee command ...
1
vote
2
answers
2k
views
Run command once and filter output in multiple files [duplicate]
Is there anyway to redirect filtered output to multiple files by running mycommand.sh only once?
Example output should be similar to this:
mycommand.sh | grep --line-buffered -B 1 A >> file1 ; ...
- 179
1
vote
2
answers
396
views
Combine command output along with the input [duplicate]
I'd like to print command output along with its input. For example for such call as
echo "Hello world" | wc -c
I want the following output:
12,Hello world
Is there any way to do this using ...
- 151
106
votes
9
answers
70k
views
When would you use an additional file descriptor?
I know you can create a file descriptor and redirect output to it. e.g.
exec 3<> /tmp/foo # open fd 3.
echo a >&3 # write to it
exec 3>&- # close fd 3.
But you can do the same ...
- 30.1k
31
votes
6
answers
11k
views
Pipe to multiple files in the shell
I have an application which will produce a large amount of data which I do not wish to store onto the disk. The application mostly outputs data which I do not wish to use, but a set of useful ...
- 1,135
61
votes
3
answers
11k
views
What is the portable (POSIX) way to achieve process substitution?
Some shells, like bash, support Process Substitution which is a way to present process output as a file, like this:
$ diff <(sort file1) <(sort file2)
However, this construct isn't POSIX and, ...
- 7,530
10
votes
4
answers
10k
views
Command redirection to multiple files: command >file1 >file2
I have this command:
cat somefile >file1 >file2
After I executed this command I can't figure out why file1 has nothing in it. It should have the output of the first file (somefile), but ...
- 101
5
votes
5
answers
1k
views
evaluate multiple patterns from program output and write into pattern specific files
I have a script outputting some value/numbers and I want to split those into two files. I am looking at something like:
./runme.sh | grep 'ook' >> ook.out | grep 'eek' >> eek.out
Where ...
4
votes
1
answer
6k
views
How to pipe a command output to multiple programs
I'm using FFmpeg and I have made a custom application which is a TCP server. I 'm using duplicate output in ffmpeg.
What I want is, for each output I want to start my program to listen on a specific ...
- 143
2
votes
2
answers
6k
views
how to move (not copy) files from one server to another?
I want to move files from server1 to server2.
A producer on server1 will keep generating the files, and a consumer on server2 will keep processing them.
I can copy files using the following shell ...
- 295
4
votes
1
answer
3k
views
How to read from stdin in process substitution? [duplicate]
I would like to send stdout to multiple commands, however I'm not sure how do I read from standard input within process substitution?
My attempts:
$ echo foo >(cat /dev/stdin) >(cat /dev/stdin)...
- 21.5k
3
votes
1
answer
4k
views
Write data to both a file and a serial port — can I use tee?
I am trying to take the input from a serial port and write it to a file and also then read the file and send it back out the serial port to the host computer. A coworker suggested using the "tee" ...
- 31
6
votes
2
answers
2k
views
dash: Pipe STDIN to multiple commands and their output to STDOUT in defined order
At first I thought this answer was the solution, but now I think I need a temporary file as buffer.
This works unreliably:
#!/bin/sh
echo 'OK' |
{
{
tee /dev/fd/3 | head --bytes=1 >&...
- 262
1
vote
1
answer
808
views
Redirect back to stderr in shell
Somewhat re-asking my question since I mistakenly asked in SO with a bash shell tag and figured this is a more appropriate place.
I'm writing a shell script within AWS DataPipeline that connects to a ...
- 625
1
vote
1
answer
2k
views
Piping to multiple awk commands
I'm trying to pipe the output of one command to two different awk commands. Following this post I am using tee and process substitution. However, I can't see the output for the substituted process.
...
- 17