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

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37
votes
5answers
14k 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, ...
33
votes
8answers
7k 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: ...
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 ...
16
votes
3answers
2k views

How to “less” a file named “-”?

I accidentally created a file with the name - (eg, seq 10 > -). Then I tried to use less to view it, but it just hangs. I understand that this is happening because less - expects input from stdin, ...
15
votes
1answer
628 views

Make program first read from pipe, then from keyboard

Consider the interactive program interactive. I have to run this program fairly frequently, and each time I run it the first few commands are the same. Obviously, having to type those commands over ...
15
votes
4answers
6k views

“openssl dgst -sha1” producing an extraneous “(stdin)= ” prefix and trailing newline

If you run this command on your Unix echo -n "foo" | openssl dgst -sha1 You will get this output: (stdin)= 0beec7b5ea3f0fdbc95d0dd47f3c5bc275da8a33 (followed by a newline). How can I force ...
12
votes
3answers
2k views

Why do some commands not read from their standard input?

I wonder what when we should use pipeline and when we shouldn't. Say for instance, to kill certain process which handling pdf files, the following will not work by using pipeline: ps aux | grep pdf ...
12
votes
3answers
2k 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 ...
9
votes
2answers
447 views

Bash: process substitution and stdin

The following line is obvious: echo "bla" | foo | bar But does the ones below do the same? echo "bla" | bar <(foo) echo "bla" | bar < <(foo) Which of the foo and bar read "bla" from ...
9
votes
2answers
307 views

How a piped shell programs balance their output/input rates? [duplicate]

Possible Duplicate: Bash while loop and reading from pipe I come from web programming background, and find myself interested in one peculiarity of using a local shell. I understand that ...
8
votes
2answers
2k views

Piping data to a process's stdin without causing EOF afterward

I have an executable that starts a user-interactive shell. I would like to, upon launch of the shell, inject a few commands first, then allow the user to have their interactive session. I can do this ...
8
votes
3answers
4k views

How do I make python programs behave like proper unix tools?

I have a few Python scripts laying around, and I'm working on rewriting them. I have the same problem with all of them. It's not obvious to me how to write the programs so that they behave like ...
8
votes
1answer
2k views

background process pipe-input

if i want to display "aaa" on screen: (1)$: echo aaa | cat ... works OK (2)$: echo aaa | ( cat ) ... works OK (3)$: echo aaa | ( cat & ) ... NOT working ...
7
votes
2answers
3k views

what is meant by connecting STDOUT and STDIN?

This is a newbie question. I'm reading a book, it says: Every process has at least three communication channels available to it: “standard input” (STDIN), “standard output” (STDOUT), and ...
7
votes
3answers
1k views

Construct a command by putting a string into a tty

I managed to do this echo -n "command" > /dev/tty1 The letters appear, and the cursor moves, but they are "ghosts" - if you hit enter, nothing happens (they are not in stdin). Edit: In the ...
7
votes
3answers
3k views

Bash: interactive remote prompt

I have a script which connects to a remote server and check if some package is installed: ssh root@server 'bash -s' < myscript.sh myscript.sh: OUT=`rpm -qa | grep ntpdate` if [ "$OUT" != "" ] ; ...
6
votes
3answers
272 views

How to create merged input (stdin) for a program

Consider such script: echo a echo b echo c It will produce 3 lines and now I can run it like this: abc_script | real_program real_program will get in its input those 3 files. However, there is a ...
6
votes
2answers
1k views

linux stdbuf - line-buffered stdin option does not exist

The man page for the stdbuf command states that line-buffered mode is invalid as a standard input buffering option. What is the reason for this? tail -f access.log | stdbuf -iL cut -d' ' -f1 | uniq ...
6
votes
5answers
639 views

Is it possible to feed Open Office via STDIN?

I have an Open Office Spreadsheet document stored inside a bash variable. I want to do something like the following to feed Open Office via STDIN: echo "$openOfficeDoc" | ooffice But it doesn't ...
6
votes
2answers
15k views

nohup: ignoring input and redirecting stderr to stdout

I am starting my application in the background using nohup as mentioned below - root@phx5qa01c:/bezook# nohup java -jar ./exhibitor-1.5.1/lib/exhibitor-1.5.1-jar-with-dependencies.jar -c file ...
6
votes
2answers
2k views

Pipe Password to Application When Asked

The following should be done in a bash script: curl --digest --user schmijos https://bitbucket.org/u/p/get/tip.zip -o tip.zip How can I automatically submit a password to curl when it asks for it? ...
6
votes
3answers
3k views

Bash script that reads filenames from a pipe or from command line args?

I want my script to read a bunch of filenames (which may have spaces) given either as a glob or from STDIN and do stuff with them. I've been able to read either way separately, but not combine them. ...
6
votes
1answer
705 views

bash scripting - read tarball from stdin

I have a task I need to script that I feel should be stupidly simple, but I'm actually having a rather tough time. I have a short bash script that takes a specific type of application in tarball form ...
6
votes
1answer
159 views

Terminal does not accept pasted or typed lines of more than 1024 characters [duplicate]

When I enter text on stdin in an OS X Terminal, a single line is limited to 1024 characters. For example, cat > /dev/null beeps after I type (or paste) a line longer than this, and refuses to ...
6
votes
3answers
75 views

Peek at the contents of stdin

I'm trying to debug a Linux application that can receive commands via stdin, and it would be really useful to be able to see everything that gets written to stdin. My first approach was to execute ...
5
votes
3answers
5k views

stdin, stderr, redirection and logs

Is there a difference between those two lines ? /home/user/script.sh >> /home/user/stdout_and_error.log 2>&1 /home/user/script.sh 2>&1 >> /home/user/stdout_and_error.log ...
5
votes
3answers
245 views

Echoing stdin when running an ed(1) script

Given the following ed script, $ cat helloworld a hello world . ,n ,s,o,O,g ,n Q I would like to obtain somehow the interactive output $ ed a hello world . ,n 1 hello 2 world ,s,o,O,g ,n 1 ...
5
votes
3answers
455 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 ...
5
votes
1answer
974 views

How to pipe text for a Mutt email body, then edit the email interactively?

I've been trying to figure out how to start Mutt in such a way that it's just like starting up an interactive Mutt and creating a new email, then copying the output of git request-pull into the body ...
5
votes
1answer
43 views

IO and other shell commands when a program is not started by a terminal

I have several launchers on my desktop for various programs, and there is a "run in a terminal" setting for those launchers. When I check that setting, the program runs from a terminal, and logs its ...
4
votes
3answers
691 views

Bash, name of the stdin file?

I have to write a bash script which will count symbols like "<" and ">" from stdin. For example: $ ./myscript.sh <example.html > - 20 < - 21 Found mismatching brackets! I did this: ...
4
votes
4answers
439 views

How can I get the size of stdin?

I'm about to compress a large directory and I want to know how large, exactly, the resulting file will be. I've tried using du: $ tar -cv dir | du -h - du: cannot access '-': No such file or ...
4
votes
2answers
812 views

using _< instead of < for stdin using bash

What is the difference between using _< and < for stdin when using process substitution. This is done using bash. Example: read bytes _< <(du -bcm random_iso.iso | tail -1); echo ...
4
votes
2answers
461 views

Is there a way to 'tee' input to a program or script?

I'm trying to find a way to use an input file for a program in such a way that I can also use stdin. For example, say I have a SQL script that creates a table. I invoke it like this: mysql -p ...
4
votes
2answers
1k views

Can I read and write to the same file in Linux without overwriting it? [duplicate]

Possible Duplicate: How can I make iconv replace the input file with the converted output? I frequently connect to amazon ec2 using their public DNS names ...
4
votes
3answers
418 views

processing command output line by line, without mixing standard input

So, I have a problem very similar to Bash: How to read one line at a time from output of a command?, I am doing: while read path; do mplayer $path; done < <(find-me-random-mp3s) or ...
4
votes
5answers
2k views

How to use filename arguments or default to stdin, stdout (brief)

I want to handle filenames as arguments in a bash script in a cleaner, more flexible way, taking 0, 1, or 2 arguments for input and output filenames. when args = 0, read from stdin, write to stdout ...
4
votes
4answers
2k views

Getting stdin from a named pipe

What I am trying to do is run python in a terminal window and redirect it's stdin from a named pipe. Then I write to the named pipe in another terminal and have that command execute on python. ...
4
votes
3answers
1k views

Create a virtual file that is actually a command

Is there any way to create a virtual file, such that reading from the file actually reads from the stdout of a command; writing to the file is acually writing to the stdin of a command? So far I have ...
4
votes
1answer
8k views

Linux : how to redirect stdout & stderr to logger?

I have a program I need to run at startup, it has output on stdout and stderr that I want to redirect to the system log using the logger command. What I have in my startup script is thie: ...
4
votes
3answers
3k views

How to get mplayer to play from stdin?

Why doesn't this work? cat /dev/video1 | mplayer - If I could get that to work, then I could play & record video at the same time using 'tee' to feed mplayer and mencoder. I want to play live ...
4
votes
1answer
798 views

In a script, check if standard input comes from a file or pipe

I know this has been poorly covered previously, but those answers either lack explanation or don't apply. Basically at some point my scripts needs check if a file is specified, if it was it will be ...
4
votes
2answers
902 views

Piped input to nano

Why does ls | nano - open the editor in Ubuntu but close the editor and save a file to -.save in CentOS? How can I get nano in CentOS to remain open when reading stdin?
4
votes
2answers
143 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 ...
3
votes
3answers
190 views

How can a command have more than one output?

In this answer, at the very bottom, Gilles mentions that a command can have more than one output or input. Yes, there's cat foo bar | something, for having both foo and bar as inputs, and there's tee ...
3
votes
3answers
277 views

How to send part of the data through the pipe/file and later interactively?

I have a command I want to run, let's call it program. It is an interactive program similar to bash or python REPL. I want to start this program with some predefined input. I tried program << ...
3
votes
2answers
98 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 > ...
3
votes
4answers
138 views

Provide strings stored in a file as a list of arguments to a command?

I install a list of URLs in a text file named myurls: http://www.examples.com/1 http://www.examples.com/2 http://www.examples.com/3 How shall I pass these URLs to wkhtmltopdf as inputs? The direct ...
3
votes
3answers
54 views

Wait for key in shell script that may get piped to /bin/bash

Consider the following shell script echo foo; read; echo bar Running bash my_script outputs 'foo', waits for the return key and outputs 'bar'. While this works fine running it that way, it doesn't ...
3
votes
2answers
1k views

Simulate empty STDIN to detached command

i want to detach command either with 'command &' in the end, or with 'nohup command &', but it stops right after detaching it. command is little specific, if it receives eof on input, it ...