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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6
votes
1answer
60 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 ...
0
votes
2answers
17 views

How to pass password to mysql command line

I have MySQL password saved on a file foo.php, for example P455w0rd, when I try to use it: $ cat foo.php | grep '$dbpwd=' | cut -d '"' -f 2 | mysql -U root -p mydb -h friendserver Enter password: ...
11
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 ...
3
votes
2answers
43 views

Remove data from the STDIN stream buffer of another TTY session

I encountered a problem the other day while running multiple tty sessions in separate terminal windows. I was running a expensive disk access command and was waiting for it to return. Meanwhile I was ...
0
votes
1answer
37 views

OpenVPN via systemd fails with stdin error

OpenVPN starts and runs just fine when I invoke it directly from the command line, but when I try to start it as a process via systemd, it throws a failure error that I can't find a solution to. ...
-1
votes
1answer
25 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?
4
votes
1answer
78 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
963 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 ...
1
vote
1answer
37 views

Bourne shell: ignoring certain kinds of stdin

I have a program that is currently working, but I need to modify it to ignore some stdin that is not fitting for its correct function. Right now, to run the program: printf "1\n3\n5\n" | sh prog The ...
5
votes
3answers
218 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 ...
0
votes
0answers
30 views

stdin read notification

I want to detect when/if an application issues read(stdin, ...). Is it possible to use unbuffered I/O so that I could wait on write in external process? The problem: Some commands require user input ...
1
vote
2answers
1k views

run a remote process via autossh in background

In Ubuntu I'm trying to run the geany editor on my local X display via the command: autossh -o StrictHostKeyChecking=false -XCg me@otherDYNDNShost geany & Trouble is, after the first ...
3
votes
1answer
44 views

Question about interactive detection in bash

I have a question about interactive detection in bash. The following script prints if it is called in interactive mode or not. $ cat int.sh #!/bin/bash if [ -t 0 ]; then echo "interactive" ...
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 ...
36
votes
5answers
12k 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, ...
1
vote
2answers
47 views

Using find and aspell together

I'm trying to spell check all the *.md files in my current directory but the following command fails: >> find . -maxdepth 1 -name "*.md" | xargs -I {} aspell check {} xargs: aspell: exited with ...
5
votes
3answers
381 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 ...
17
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 ...
1
vote
2answers
94 views

Stdin Input Behavior Between “cat” and “less”

When I issue cat, the terminal hangs waiting for stdin input. However, when less is issued, I get Missing filename ("less --help" for help). It is known that both less and cat accepts stdin input. ...
0
votes
1answer
275 views

Command that prints file contents given filename on stdin

I have a command that produces some output part of which is actually a file name containing the full output data. I want to extract the file name (which I trivially do with cut) and then pass it to ...
3
votes
1answer
138 views

Run vsim from dmenu — it only works when directly invoked in the terminal

Works: vsim, sh -c vsim Doesn't work: echo "vsim" | sh, echo "vsim" | xargs -I {} sh -c "{}" I want to run ModelSim (vsim) with dmenu, which is triggered using xbindkeys. Details vsim is a ...
1
vote
2answers
788 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
1answer
115 views

Can pocketsphinx_continuous read from stdin?

There is one parameter -adcdev "Name of audio device to use for input.", but it doesn't say if this can be stdin. Can pocketsphinx_continuous read from stdin?
0
votes
2answers
330 views

cat STDIN won't work twice in script

I have a script that outputs various information and the text fields of an html form (method POST). When I attempt to cat <&0, it displays properly. However a few lines down, I try to cat ...
0
votes
0answers
117 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 ...
0
votes
6answers
105 views

What are some practical uses of STDIN redirection? [closed]

I am having a very difficult time trying to think of a single practical use for STDIN redirection. cat < /etc/passwd is an example of STDIN redirection, but it is silly in the same way as a useless ...
1
vote
1answer
87 views

What is happening while executing this command cd / | vi?

When I execute the command cd / | vi, it goes to the vi editor. When I type any command it does not display the command but it gets executed and the command that is executed is not shown in the ...
9
votes
2answers
367 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 ...
4
votes
3answers
2k 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 ...
1
vote
1answer
71 views

Is bluetooth keyboard associated with `stdin`?

I know that keyboard is standard input and is referred by the stdin file. I sometimes use a Bluetooth(BT) keyboard when working on my laptop. Both keyboards, my laptop keyboard as well as the BT ...
3
votes
1answer
198 views

How does `stdin` of linux work?

I know that stdin refers to standard input in linux, usually the keyboard. It can also be referred by file descriptor 0. So, which file descriptor does the (standard input) mouse refer to? Or is it a ...
3
votes
1answer
85 views

Does cat never read from terminal?

Chapter 43. Redirecting Input and Output of Unix Power Tools, Third Edition has to say this about cat command: Standard input (stdin) normally comes from your keyboard. Many programs ignore ...
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 > ...
29
votes
4answers
6k 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: ...
1
vote
1answer
97 views

Bash script and stdin

I am having a C program which requires to read from stdin. This is one of the requirements, and it cannot change. I have written a simple bash script that creates all the directories I want, handles ...
9
votes
2answers
296 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 ...
1
vote
1answer
184 views

Identify python script is waiting for a manual input

I'm writing a shell script which executes a Python script. The Python script halts for a manual enter to be provided. However, I don't wan't to have to press enter each time to the script. Instead, I ...
4
votes
2answers
739 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 ...
5
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. ...
5
votes
3answers
4k 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 ...
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 ...
6
votes
5answers
542 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 ...
3
votes
1answer
6k 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: ...
2
votes
3answers
222 views

How do I make pasted shell commands invisible?

I'm using an AutoHotkey macro to run some shell commands, i.e. ^`:: SendInput set c=".cshrc-acheong"{ENTER} SendInput set v=".vimrc-acheong"{ENTER} SendInput foreach d ( /home/acheong /home/tcama ...
3
votes
2answers
771 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
370 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 ...
0
votes
2answers
64 views

file(1) command termination when using the -f - option

Say I'd like to use the file -f - command inside a script, and send some input using the stdin, when I'm finished I'd like to terminate it gracefully, but unfortunately I haven't found any way to do ...
6
votes
1answer
667 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 ...
-4
votes
2answers
113 views

What is the utility of piping to `/dev/null`?

Seeing that /dev/null's utility isn't immediately obvious to me, what is the use of /dev/null piping?
1
vote
1answer
255 views

Bash Script which can direct stdin stream to program

I am trying to create a script capable of infinitely processing an incoming stream which is piped to it, and continuous producing an output stream which can be piped to something else something as ...