Stdout is the standard output stream is the default destination of regular output for applications.

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10
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3answers
261 views

Two Programs having their StdIn and StdOut tied

Suppose I have two programs called ProgramA and ProgramB. I want to run them both simultaneously in the Windows cmd interpreter. But I want the StdOut of ProgramA hooked to the StdIn of ProgramB and ...
1
vote
1answer
35 views

Unexpected BPython console output behaviour

I am using BPython to run Python scripts, and I found the console output has a different behavior than the regular Python console.. For example this small snippet: import time for i in range(100): ...
12
votes
3answers
24k views

Windows: Command line redirection to text file while also seeing output

I'm writing a C program in Windows, my printf calls print to the command line, and I know that I can redirect all this output to a text file using: myProgram.exe > mylog.txt However, I wish to ...
0
votes
2answers
14 views

How to terminate a cli app when stdout contains a certain string?

I've got a command line app that outputs lots of information to stdout. How can I terminate the program when stdout contains a certain string? e.g. something like: my_program | ...
0
votes
0answers
30 views

See contents of conhost

Every now and then, various programs create conhost.exe processes on my (Windows 7 x64) computer. I know they are console windows, except the windows themselves are hidden. I don't suspect any ...
0
votes
1answer
38 views

how to see the output of a cron/at jobs while it is still running?

The output of a cron or atq job is automatically send by email to the user, when the job is finished. However I am running a time consuming script, and I would like to check that it is running ...
23
votes
9answers
15k views

Log rotation of stdout?

I have a Linux program which can write information to stdout and stderr. I have a shell script which redirects that output to a file in /var/log. (Via >> and 2>&1.) Is there a way to ...
2
votes
1answer
51 views

PowerShell v5: Suppress Out-Default output in nested functions

I'd like to suppress any output then function_b is invoked: Function function_a { "test" | Out-Default } function function_b { [CmdletBInding()] param() function_a } # These are ...
1
vote
0answers
18 views

Parsing (or Converting) Buffered Output

If a dynamic, text-based, CLI application doesn't include an option for producing unbuffered text output; what options do I have for parsing said output? Can it be converted to a more appropriate ...
1
vote
1answer
68 views

Redirect STDERR and STDOUT to file with timestamp on each line

On my CentOS I am trying to execute a php script that contains an endless loop to do some fancy stuff inside. It doesn't matter that an endless loop may not be an accurate solution for most cases, but ...
0
votes
1answer
38 views

How to stop background processes from outputting permanently?

In my newly installed Lubuntu virtual machine terminal, when I run firefox & firefox runs in the background, but it keeps on outputting in my terminal. I found a way to stop it from another ...
0
votes
1answer
119 views

How to echo only 1st line from 'curl' command output?

I'm trying to get only first line of the curl command output. (Sorry if this is confusing) Let's say, for an instance, i run simply: # curl http://localhost <!-- This is the hidden line i want to ...
1
vote
2answers
34 views

How to unset a “>” echo in Linux

I've just realized I don't know how to unset an echo I set with >. The exact current situation is I just set dmesg > /var/log/syslog and now wanted to unset it, realizing I've never done that ...
0
votes
0answers
53 views

stdout of my app visible in cygwin bash.exe, and not visible in mintty.exe

I have a simple c program with printf("start\n");. When I run it from bash.exe -i -l, I can see the stdout. When I run it from mintty.exe, I can't see it. How can I make it visible thru mintty.exe as ...
1
vote
1answer
144 views

reading stdout in pipeline using “-” fails for “docker exec”

I want to launch a bash terminal for my Docker instance by piping the first container ID to docker exec: docker ps | head -2 | grep -v CONTAINER | cut -d' ' -f1 | docker exec -i -t - bash The final ...
46
votes
2answers
21k views

Can I make cURL fail with an exitCode different than 0 if the HTTP status code is not 200?

I was always assuming that when curl got an HTTP 500 response it was returning an exit code that meant failure (!= 0), but that seems to be not the case. Is there a way I can I make cURL fail with an ...
2
votes
4answers
200 views

python2.7 from macports stdin issue

My python2.7 from macports seems to mess up with osx terminal in a weird way. Here is what I mean. The exact input from the keyboard was: /opt/local/bin/python2.7<ENTER> a = 3<ENTER> a&...
3
votes
2answers
2k views

What is the use of binary output on stdout?

Some programs print their binary output directly on stdout. Here are some examples: tar -c file.png dd if=file.png Well, I see that the output can be redirected to a file. But these programs ...
51
votes
5answers
40k views

How do you redirect wget to standard out?

I have a crontab that wgets a PHP page every five minutes (just to run some the PHP code), and I want to send the output to standard out. I couldn't find it in the wget manual. I'm looking for ...
0
votes
1answer
101 views

How to get stdout of a “lost” session

I don't well what's the name of the situation, I think yesterday I closed a session with a background ipython process, but I am still able to connect to it (the process is running a web server and I ...
2
votes
1answer
1k views

shell standard streams redirection order OR 2>&1 1>/dev/null vs 1>/dev/null 2>&1

Can somebody please clarify differences? Is some of those considered as best practice? If I remember correct I somehow on SO read that this 1>/dev/null should precede this: 2>&1 ls -al /...
0
votes
1answer
27 views

Weird result of initiating a variable with the output of 'git describe'

For some reason this assignment: OUT=$(git describe HEAD) prints to the stdout (for example): fatal: No names found, cannot describe anything. Is this a normal behavior? Why doesn't this happen with ...
10
votes
2answers
12k views

How to tar/untar the output on the fly

What is the idiomatic way to do the following tar to stdout read this tar output from stdout and extract to some other folder. My solution is tar --to-stdout .. | tar -C somefolder -xvf - But ...
0
votes
1answer
50 views

Modify terminal STDOUT/STDERR to change the line colour based on a REGEX

Is this possible? What I would like to achieve is when running unit tests (Python) to highlight any line which matches the path to the current project directory and leave other output untouched. ...
0
votes
2answers
168 views

Redirect stderr to second terminal / tty

I've tried things like rse to differentiate standard-output and standard-error streams from a program; but I'd really like the option of viewing the two in separate terminals, without redirecting to a ...
3
votes
3answers
4k views

Encrypting to standard output with gnupg

I'm trying to encrypt something with gpg -a and return the result to standard out rather than a file. According to the manual, it should be sufficient to omit an --output flag, but that doesn't seem ...
0
votes
1answer
352 views

Using PuTTY SSH, how do I capture the remote output of a command?

In Linux ssh me@server "echo this ran remotely" The output this ran remotely is put to standard out. This is perfect. In Windows echo "echo this ran remotely" > test.cmd putty -i privatekey....
3
votes
2answers
301 views

Any way to view stdout of a program after it has been started in gnome-shell?

So, if I run a program through the menus in gnome-shell, is there a way to view stdout and stderr? Or is there some kind of hack to achieve this functionality? Or is everything just sent to /dev/null?...
0
votes
1answer
48 views

Which is the preferred approach to pass command/script arguments to a log file?

Generally, I am wondering how I can pass the arguments from a terminal command to stdout. More specifically, I am using tar as part of my backup process and I would like the parameters (especially ...
1
vote
1answer
316 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} ...
0
votes
1answer
259 views

`if` statement with stdout && passing xargs through pipe

Say I have a list.txt of files I want to check. cat list.txt and for each file, I want to perform an action cat list.txt | xargs -I {} touch {} But depending on the outcome of the action, I want ...
0
votes
0answers
1k views

bash: redirect the stderr/stdout of a running process?

I have a running process running in a bash terminal that is printing some prompt, and I would like to send it to the background with the stderr/stdout prompt that is printing either redirected to /dev/...
1
vote
2answers
34 views

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. Then,...
7
votes
4answers
4k views

Determine if output is stdout or stderr

How can I determine if what a process is outputting is stdout or stderr?
6
votes
1answer
2k views

Different output when redirecting

$ mysql -e 'select a,b from tablefoo' databasename yields +---+---+ | a | b | +---+---+ | 1 | 0 | | 2 | 1 | +---+---+ whereas $ mysql -e 'select a,b from tablefoo' databasename > file ...
0
votes
0answers
14 views

How to get stdout of another program [duplicate]

Some Linux program prog1 permanently prints to console. I'd like to read and analyse it's stdout in my C program prog2 as stdin. I can't change prog1 source. I expect something like this command: ...
1
vote
1answer
2k views

Receiving FFMPEG error -22 when piping data to stdout

I am attempting to use FFMPEG to transcode avi files to mp4 and pipe the data to stdout using the following command (technically through NodeJS, but I receive the same error when executing the ...
4
votes
2answers
4k views

Redirect stdout to a file when process is run in background

How can I redirect the stdout of a program to a file when it's run in the background? I have a program that generates output every second. When I run it normally and redirect to a file, the output ...
11
votes
1answer
3k views

Copy terminal output to Mac clipboard?

I need to directly copy the terminal stdout to the clipboard on Mac. How would I do this? Example: echo sometext | copy_to_clipboard or echo sometext > /private/clipboard.txt
1
vote
2answers
1k views

How to quieten tcpdump output when reading a pcap file?

I notice that when using tcpdump to read a pcap file, the tcpdump command somehow manages to print information to my console even when I redirect both STDOUT and STDERR. How can I prevent tcpdump from ...
0
votes
2answers
1k views

How to redirect a part of stderr and stdout to /dev/null

My program outputs to stderr and stdout. I want to grep for "pattern" either in stderr and stdout. And I want the rest to be sent to /dev/null. If I pipe after redirect stderr : ./prog 2>/dev/null ...
1
vote
2answers
465 views

Stdout and stderror in CentOS

I am exec command: yum info mcrypt | grep -i error > /dev/null yum info mcrypt | grep -i error 2> /dev/null But i see: Error: No matching Packages to list How I can hide this messasge ...
6
votes
3answers
4k views

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 ...
2
votes
1answer
325 views

Using the same file as stdin and stdout results in empty file

If want to filter a file but if I use the same file as input and output the output file is empty. Is there another solution instead of using a second file? php -r "echo preg_replace('~/\* DEV \*/(.*)/...
2
votes
1answer
972 views

How can I pipe the output of *all* entered shell commands into another? (e.g. pipe everything into 'lolcat')

Good Afternoon, (OS X user) I am specifically trying to pipe the output of every shell command I type into the ruby gem 'lolcat' (which makes the output to the terminal rainbow colored). Is there a ...
2
votes
1answer
330 views

What happens if dd encounters errors while output of dd is being piped to gzip?

Suppose that dd if=/dev/sda bs=100M | gzip -c > somefile.img.gz is done. If errors occur in dd, do I get to see error messages in terminal, or do they get ignored? Also, suppose that dd ...
19
votes
3answers
3k views

Why does the output of some Linux programs go to neither STDOUT nor STDERR?

Why does the output of some Linux programs go to neither STDOUT nor STDERR? Actually, I want to know how to reliably capture all program output, no matter what 'stream' it uses. The problem I have is ...
2
votes
4answers
8k views

How can I stop cat output immediately despite massive output?

I'm looking for someway to stop the output to STDOUT when I realize a command is wrong. For instance, if I accidentally cat a very large file. Usually it will eventually stop if you hold down ctrl + c,...
21
votes
2answers
13k views

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 ...
1
vote
3answers
2k views

zcat | head : write error from large gz file

I was trying zcat to get only the first 1M lines of a compressed .gzip file into a new one. However, I get the following error: $ zcat path/to/R2.fq.gz | head -100 >R2.fqtest head: write error: ...