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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0
votes
4answers
47 views

How to log from inside the script along with stdout

I am aware that I can log using tee But I want to log from inside my script, at the same time display the content on the stdout. Example, my code looks something like this: names=$(print("name1 ...
6
votes
5answers
1k 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, ...
8
votes
2answers
9k views

Execute command in remote active terminal

Suppose you have a terminal emulator (T1) open with a PID of 6350. From another terminal, type this command (C1): echo "ls\n" > /proc/6350/fd/0 This writes ls and the new line in T1 but does ...
2
votes
2answers
42 views

Output is in console but not part of stdout or stderr

I have a command that outputs the following: READY Listening.... HELLO READY Listening.... TEST It is speech recognition from pocketsphinx_continuous. I need that output redirected to a file, and ...
3
votes
5answers
164 views

Concatenate contents from stdout and from file

How can we concatenate results from stdout (or stderr) and a file into a final file. For example ls -a | grep text1 concatenate with file2.txt into a final result (not file2.txt), without storing ...
16
votes
4answers
713 views

How to trick a command into thinking its output is going to a terminal

Given a command that changes its behaviour when its output is going to a terminal (e.g. produce coloured output), how can that output be redirected in a pipeline while preserving the changed ...
3
votes
3answers
32 views

What is regarded as “ideal” in relation to using stdout/stderr for output in different situations?

I have seen stdout and stderr used in a variety of different ways - as far as I understand, it is common to use stdout for general information and stderr for errors and the like. However, I have also ...
19
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
4answers
163 views

How to display output of command while also parsing it?

I have two commands, build and deploy. Currently I run build manually, parse its output using my own eyes, and use a value I find in the output as an argument to deploy. The process looks something ...
0
votes
1answer
33 views

vimdiff to compare output instead of files

I am trying to compare two command output (no files) vimdiff "$(tail /tmp/cachain.pem)" "$(tail /etc/pki/ca-trust/extracted/pem/tls-ca-bundle.pem)" I tried playing with redirection, pipe, and vim - ...
5
votes
4answers
1k views

Reuse last line of output from shell command

I am compiling something and depending on success (last line of output contains "success"= I want to scp the binary to the target. I'd prefer a piped oneliner. Is there a way to do this?
0
votes
0answers
19 views

Piped sequence - printing

I need to write a piped sequence of commands that prints out a list of all sub directories of a current directory. In order to get all sub directories of a current directory I use: ls -D Since I am ...
0
votes
2answers
78 views

how to redirect output of ssh to a file

I want to make ssh connection to my server but I don't want to enter password. I want to save output to a file like so: $ ssh root@x.x.x.x -p 22 1>output 2>&1 but when I run it the output ...
0
votes
0answers
83 views

Stop stdout log being clipped (by heroku-local)

I run heroku local with the Procfile: web: start-nginx gunicorn -c gunicorn.conf.py app:app start-nginx does some environment setup, and then ends with: { nginx --some-params & $@ ; } the ...
2
votes
2answers
302 views

pipe stdout-to-file with wc

I'm working on a lab assignment for a class, which exemplifies users | wc -w as displaying the number of users currently logged in. The instructor has asked we write the output of users to a file ...
0
votes
2answers
39 views

Unclear where bash output is going

I made a small script to output the list of vim plugin remotes to a file, so I could figure out what ones I want to keep or remove. However, when I run it, the output doesn't get piped to the file. ...
0
votes
2answers
73 views

Printing on “standard out” and “standard error”

I'm puzzled over some terminology used in my homework: So, the way I understand the question is that I should print echo, cat, etc., which I would do like with the echo command, for example echo ...
1
vote
2answers
89 views

Duplicate stdin to stdout and stderr, but in a synchronized way

I need to duplicate the stdout of a producer and feed it to two consumer in a synchronized fashion. consumer 1 producer | duplicator | consumer 2 ...
0
votes
0answers
24 views

fs_usage: a part of stdout is missing.. Where did it go?

I'm using $ fs_usage -f diskio to spy on processus when I hear my hard drive spinning for no reason, so that I know who is working so hard.. Here is one sample line: 16:14:13.785568 ...
1
vote
1answer
68 views

How to know if output is being redirected to a file? [duplicate]

I am working on displaying output like ls command (just ls, no options). And I have a working program using the system calls. But I experienced a strange behavior while testing as shown below. $ ls ...
6
votes
3answers
261 views

Are unix[-like] programs capable of determing where their output is going? [duplicate]

Up until recently I was under the impression that Unix-y programs were unaware of where their output went, be it to standard out, redirected to a file, or into a pipe. However, an unrelated U&L ...
6
votes
2answers
98 views

Notification Listener Behaving Strangely when Backgrounded

I've been struggling to get my IRC-Bouncer/Notification Script working. This is meant to be a script which will automatically login to a remote machine, attach to a screen session (or start one if ...
1
vote
4answers
937 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 ...
1
vote
3answers
152 views

in bash script; a process stdout as filename argument fails when you open it more than one time

Consider this bash script code: #!/bin/bash function bug_part() { cat $1 > sample.first cat $1 > sample.second #second time you open file $1, it contains no data } bug_part <(echo ...
1
vote
1answer
120 views

Prevent ssh-keyscan from generating output

Problem: When running ssh-keyscan in cron it emails me the output of ssh-keyscan every day. The email simply contains the following. # <hostname> SSH-2.0-OpenSSH_5.3 My (simplified) cron ...
36
votes
8answers
10k views

How to do nothing forever in an elegant way?

I have a program which produces useful information on stdout but also reads from stdin. I want to redirect its standard output to a file without providing anything on standard input. So far, so good: ...
4
votes
2answers
246 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 ...
50
votes
6answers
6k views

Can I configure my shell to print STDERR and STDOUT in different colors?

I want to set my terminal up so stderr is printed in a different color than stdout; maybe red. This would make it easier to tell the two apart. Is there a way to configure this in .bashrc? If not, is ...
2
votes
5answers
2k views

How to add new lines when using echo

Why the following command does not inserts new lines in the generated file and what's the solution? $echo "Line 1\r\nLine2" >> readme.txt $ cat readme.txt Line 1\r\nLine2
1
vote
3answers
96 views

How to write a script that can take input from stdout

I want to be able to write a script that can take stdout as an argument, if anything is piped into it (ultimately, I would like it to be polymorphic) - The trouble is, I have searched and searched ...
3
votes
2answers
256 views

How do I filter stdout of a program through grep while still controlling the program?

I'm trying to filter the output of the mpv media player, removing a particular line, but when I do so I am unable to control mpv with the keyboard. Here is the command: mpv FILE | grep -v 'Error ...
1
vote
1answer
30 views

Pipe stdout to obexftp bluetooth transfer?

Here I have command to transfer inputFile.tar to another bluetooth device (10:68:3F:57:7D:B6). obexftp -b 10:68:3F:57:7D:B6 -p inputFile.tar However, is it possible to use stdout as input for ...
1
vote
1answer
82 views

How to redirect tarsnapper output to /dev/null?

I use tarsnapper's make command for managing tarsnap backups like this: tarsnapper -c /usr/local/etc/tarsnapper.conf make Which works like it should and I get an output like this Creating backup ...
0
votes
1answer
39 views

How to redirect the time a task takes to complete into a log file, given that such task is already redirecting?

I have a shell script running a python task, whose stdout is being redirected to a log file: python script.py >> log.txt I wish to also log the time this task takes to complete, into the same ...
0
votes
3answers
55 views

What is `>&` in simple terms? [duplicate]

What does $ command 1>&2 do? As I understand it this runs the command but with the STDOUT redirected to the STDERR. But I'm not sure exactly how >& works. I have seen it as $ command ...
-1
votes
1answer
47 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 ...
4
votes
3answers
529 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
vote
0answers
24 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
34 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?
3
votes
1answer
127 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
100 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 ...
1
vote
3answers
110 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: ...
1
vote
1answer
124 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 & ...
4
votes
3answers
163 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.
18
votes
4answers
15k 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 ...
1
vote
1answer
299 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 ...
41
votes
5answers
18k views

Can I pipe stdout on one server to stdin on another server?

stdout on one CentOS server needs to be piped to stdin on another CentOS server. Is this possible? Update ScottPack, MikeyB and jofel all have valid answers. I awarded the answer to Scott because, ...
0
votes
1answer
285 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 | ...
5
votes
3answers
590 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 ...