stdout is the name of the default output file descriptor of a process. Since there is nothing special about `stdout`, you *should not* use this tag. Use [tag:io-redirection] for questions on how to redirect output, use [tag:file-descriptors] for questions on how to manage file descriptors, use ...

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4
votes
3answers
93 views

Why can't I read /dev/stdout with a text editor?

I just started learning how Everything Is A FileTM on Linux, which made me wonder what would happen if I literally read from /dev/stdout: $ cat /dev/stdout ^C $ tail /dev/stdout ^C (The ^C is me ...
-1
votes
1answer
19 views

How to get the screen logs of a oracle VM [closed]

When I start an oracle VM with Linux operating system I want to get the standard output, i.e whatever is coming in the screen. Is there any tool or is there any way to get that so that I can check ...
1
vote
0answers
22 views

How to get stdout of process? [duplicate]

I started a process from the command line, but the window server died. However I see the process I started is still running. Is it possible to connect a terminal to the process to see its output? ...
-1
votes
1answer
26 views

Does those two constructions do the same thing: proces <input.txt vs cat input.txt | process in Linux

Does those two constructions do the same thing: proces <input.txt vs cat input.txt | process in Linux?
2
votes
1answer
29 views

Is there any way to exit “less” follow mode without ^C?

Often times I find myself in need to have the output in a buffer with all the features (scrolling, searching, shortcuts, ...) and I have grown accustomed to less. However, most of the commands I use ...
1
vote
1answer
32 views

Using GNU timeout when redirecting stdout to file

Suppose I have a executable which for which I want to log STDOUT and STDERR to separate files, like so: python write.py > out 2> err When I use this command with GNU timeout, my out file is ...
4
votes
1answer
79 views

uniq and bash for loop not writing to stdout before stdin closing (for one-line website visitor notification system)

I'm trying to trigger a beep on the PC speaker for every unique visitor of a website. After some brainstorming, it seemed to be possible with one line: for e in `ssh me@mymachine "tail -n 1 -f ...
1
vote
3answers
83 views

Store stdout and stderr in file, then recreate the output later

I've redirected output to a file like so: $ ./test.bash 2> >(sed 's/^/stderr: /' >> output) > >(sed 's/^/stdout: /' >> output) $ cat output stdout: Hello World! stderr: ...
4
votes
3answers
116 views

How to not show the stdout output of a running process?

When a running process gives lots of stdout output throughout its lengthy running process, you don't want to kill it and rerun it. How can you not show the output? Thanks.
0
votes
0answers
48 views

How to use stdout/stderr from multiple program

I'm working with Docker-containers. An important part of Docker is to log error, etc., to stdout/stderr. For example, I want to run the following program by using this command: nginx -g "daemon ...
16
votes
4answers
3k views

Write Python stdout to file immediately

When trying to write the stdout from a Python script to a text file (python script.py > log), the text file is created when the command is started, but the actual content isn't written until the ...
20
votes
2answers
1k views

Pipes, how do data flow in a pipeline?

I don't understand how the data flows in the pipeline and hope someone could clarify what is going on there. I thought a pipeline of commands processes files (text, arrays of strings) in line by line ...
0
votes
1answer
76 views

Redirect all bash script output (from inside the script) to two files: one append, one rewrite; but discard output to the console

I can easily redirect both standard and error output of a bash script to the file, while discarding an output to console with simple exec statement: exec &>>/var/log/backup.log But how do ...
0
votes
1answer
159 views

How do I grep on a live log (stdout)?

I'm not sure if that what stdout is, but that's what I think. What I want to do is filter out a certain log message when running an executable. I tried this: Executable 2>&1 /dev/null | ...
18
votes
3answers
1k views

Is it safe to type another command into STDIN while the previous command is writing to STDOUT?

Perhaps this has been answered previously, I would welcome a link to another answer... If I execute a shell command (in a bash shell) like the following: make Then while the output from make is ...
0
votes
1answer
131 views

Redirecting Standard Output And Standard Error to One File [duplicate]

I have come to understand that we have two methods of redirecting both stdout and stderr to the same file. The first method is: ls -l /bin > ls-output.txt 2>&1 As the author of this book ...
3
votes
1answer
128 views

stdout redirect. sh: resource temporarily unavailable

I have large batches of bash processes. Each bash script invokes executeables which have their stdout redirected to distinct log files. About 5% of the runs end up with: sh: [name of log]: Resource ...
1
vote
1answer
35 views

Why does the -v option with rm show entries with a backquote and a normal quote?

When I do rm -v on a set of files, I see the output list of files being deleted with a backquote and a regular quote, eg: rm -v rsl.out.0??? removed `rsl.out.0579' removed `rsl.out.0580' removed ...
0
votes
1answer
101 views

Pipe stdout to command on stdout

If I had a running process like tail -F watch.txt and I wanted to capture the stdout from this running process and pipe it to another command on stdout how could this be done? Here's an example of a ...
3
votes
2answers
404 views

How does Bash get the output of an executed program?

When I execute a program in Bash, for example, [ls][2], it sends its output to standard output (fd &1). And the ouput of the executed program is displayed in the terminal. How does Bash/terminal ...
1
vote
1answer
40 views

capture log of ufsdump when backup to stdout

I am backing a file system with ufsdump. In order to gain space in the remote file system I backup to stdout then pipe the output to compress. I find is more efficient that backuping up and then ...
0
votes
1answer
49 views

Force ping to write before interrupt

I am trying to get ping to continuously write some times to a file. When I run $ ping 10 10.1.10.28 | perl -ne '/time=(\d+\.\d+)/ && print "$1\n"' It returns one number every several ...
1
vote
1answer
54 views

Dynamic ~/.ssh/config

I'd like make my ~/.ssh/config file dynamically generated by a shell script (or anything else that prints to STDOUT). Is there a UNIX trick to make reading a file result in executing a command & ...
0
votes
1answer
58 views

Keep PHP's output with tee -a

Normally when running PHP script in web server mode, this would show up: $ php -S 0.0.0.0:12345 PHP 5.6.1 Development Server started at Mon Nov 24 14:09:22 2014 Listening on http://0.0.0.0:12345 ...
1
vote
2answers
811 views

Redirect stdin and stdout to ports

I'd like to take a program P that reads from stdin & writes to stdout, but connect it to nc or whatever such that it reads from a certain port and outputs to another port. # The reading is easy, ...
0
votes
2answers
69 views

How can I redirect the same message to both stdoud and stderr (without temporary object)

It is easy to redirect stdout or stderr to the same output (file or one of the 2 std output) with a 1>&1,>&2 and/or >file. Is there a way to send the same output to both the std ...
3
votes
1answer
347 views

Output of a python script running as unit is out of order while shells seems unnafected

How would I get all outputs of systemd managed python2 script instantly into journal, just like it appears in terminal I'm on centos 7, but seems to be same on arch according to systemd manual, ...
-2
votes
2answers
454 views

Corresponding 7zip command for unzip -p -a

I have a question regarding unzip command in Unix. As of now my Unix command unzip -p -a is able to zip the file which are lesser in size. But if the file size is larger then the command is not able ...
0
votes
0answers
119 views

Text replace literally *all* instances of a string through stdin, stdout

Linux, or specifically Ubuntu 14.04 LTS Server if necessary (and CENTOS 6.5/7 minimal would be nice). If I enter "FOO" at the command line, (regardless of whether as a word or as a substring), I'd ...
2
votes
2answers
62 views

Output piped content to file and show number of lines in the file on stdout

I would like to use tee to pipe content from stdout and stderr respectively into files (in fact append it with > >(tee -a $filename)). However, instead of seeing the contents appended to the ...
5
votes
6answers
2k views

Command to output file content to stdout?

I know cat can do this, but its main purpose is to concatenate rather than just displaying the content. I also know about less and more, but I'm looking for something simple (not a pager) that just ...
2
votes
5answers
260 views

How to overwrite stdout using echo? [closed]

We know to overwrite bar.txt, we can use this: echo "foo" > bar.txt but how can we overwrite to the standard output? I tried this command: echo "foo" > but it failed. I want this because ...
4
votes
1answer
102 views

unexpected output with grep

I am using pyrit. For those who dont know, pyrit allows among other things to check if a wpa handshake key is valid: pyrit -r file0.cap analyze when a file does not contain a valid key, here is ...
4
votes
4answers
318 views

A command that generates both standard error and output

I want to do some troubleshooting on my bash script. Is there a short and simple command that generates both stdout and stderr so that I can use 2>&1 on it? Sorry if this looks trivial, but I ...
1
vote
2answers
209 views

Call background process back to stdout

Is it possible to "call" a background process output to be shown in the terminal? Example: cron starts apt-get to update the system and I want to see the output of apt-get
5
votes
1answer
329 views

Rotating log files while process still running

I have a process running that writes standard output and standard error to a log file /var/log/dragonturtle.log. Is there anyway to rotate the log file, and have the process continuing to write to the ...
2
votes
4answers
271 views

Command line 'buffer' [duplicate]

I wanted to tail the last 100 lines of a file to the same file, but the command tail -n 100 file > file doesn't work, I assume because the stdout gets written to the file 'live', before everything ...
1
vote
0answers
16 views

Test execution output of a command before a pipe [duplicate]

I would like to test the execution of a php script that redirect its stdout and stderr to a file with tee. php /path/to/script --param 2>&1 | tee -a /path/to/log if ( test $? -ne 0 ); then ...
3
votes
2answers
92 views

Decoding “prog > file 2>&1”

I am having some difficulty understanding the construct prog > file 2>&1. I have read that it means "Send stdout and stderr to file". But my question is how? I understand that prog > ...
6
votes
2answers
157 views

How can I pipe stdout to another program?

I'm trying to setup a linter for my code and I only want to lint the coffeescript files that have changed in the current branch. So, I generate the list of files using git: git diff --name-only ...
4
votes
2answers
464 views

How to redirect stdout to a file and read from the same file simultaneously with another task?

I want to run a task (which takes quite a long time) remotely in Ubuntu Linux Bash via nohup and redirect stdout to a file, e.g.: nohup task > out.txt & From time to time I would like to ...
14
votes
2answers
1k views

How to find out what process is writing to STDOUT?

I have two instances of a process running. One of them is "frEAkIng oUT!" and printing errors non stop to STDOUT. I want to kill the broken process but I have to make sure I don't terminate the wrong ...
1
vote
3answers
524 views

Inserting the command line text before output in stdout (for pipe / redirection)

Consider the following bash constructs: ls /usr/include/asm > list-redir.txt ls /usr/include/asm | tee list-tee.txt In this case, list-redir.txt and list-tee.txt will be identical, and will ...
2
votes
1answer
116 views

stdout is empty

When a run the command: cellprofiler --get-batch-commands "/users/pmrotem/CellProfiler/example_project/output/Batch_data5_8.h5" in the shell, I get an output: CellProfiler -c -r -b -p ...
1
vote
2answers
163 views

grep a keyword from Mplayer output and send the rest to file

I am using mplayer. I want to send everything to a log file (/tmp/server.log), but I want the Volume output to be written to the terminal. I have seen that there is a way to split the output with tee, ...
2
votes
3answers
114 views

Script needs to read echoed line

So, I need to write a Bourne-shell script, where my script has to work with the line, that was just echoed to stdout - e.g.: echo *something* | myscript.sh [parametres...] This may be a basic ...
12
votes
3answers
1k views

tee stdout to stderr?

I'd like to send stdout from one process to the stdin of another process, but also to the console. Sending stdout to stdout+stderr, for instance. For example, I've got git edit aliased to the ...
5
votes
4answers
656 views

How do I break up a file like split to stdout for piping to a command?

I have a large .sql file full of SELECT statements that contain data I want to insert into my SQL Server database. I'm looking for how I could basically take the file's contents, 100 lines at a time, ...
5
votes
3answers
384 views

Piping commands, modify stdin write to stdout

echo Hello World | nano - | less I want to modify Hello -> Goodbye while in the the text editor. It does not have to be with nano. I am stuck with nano reading stdin but requiring me to write to a ...
4
votes
3answers
1k views

Dynamically trim stdout line width in Bash

Lately, I have been experimenting with the ps command, and sometimes long paths wrap to the next line (or two) and make it hard to read. I want to pipe the ps output into another program to limit the ...