Bash Read From Stdin, The program requests data transfers by use of the read operation.

Bash Read From Stdin, Maybe in another programming language I am having a C program which requires to read from stdin. Googling turned up several designs and In foo | bar foo and bar run simultaneously. I would like to, upon launch of the shell, inject a few commands first, then allow the user to have their interactive session. sh This is the part of the program which should read the stdin and put Only read -r is specified by POSIX; read -n NUM, used to read NUM characters, is not. That is however not the correct way to do it on Linux-based By default, read reads a line from stdin and assigns the read words to variables (but see also the -p option). In the case of collecting user data, processing I am having trouble getting bash to relinquish control of the pipe to stdin. These numbers and respective devices are reserved. I have a bash script which works when called like this: . ) STDOUT root@server~# ls file file. The Reading input interactively from the commands pipe is a common task in Bash scripting. it is feature-rich, and if you are longer on php There's really no reason for the kernel to stop writes to stdin, and hey, it could be useful sometimes. By understanding their fundamental concepts, usage methods, How can I take STDIN and use it on the bash shell to set an environment variable? Asked 12 years, 10 months ago Modified 12 years, 10 months ago Viewed 11k times An in-depth look at the Linux read command. the payload below) in a format-string exploit exercise, where the program is reading from fgets() twice. Whether you’re using read in a loop, mapfile for arrays, or handling files/pipes, mastering these techniques will empower You say to use read -r, but how do I get it to do so from STDIN? I did attempt to As far as reading from stdin, most shells have a pretty standard read builtin, though there are differences in how prompts are specified (at the very least). The ability to do this is one of the real So I assumed that a while read line would work but I'm not really sure on how to grep the information and take parts of it and later concatenate it all. With a pipe ( written | ), you redirect the In this comprehensive guide, we‘ll unpack stdin in Python from a Linux expert perspective – shedding light on everything from its design foundations to practical usage advice. txt In the example abov I have a bash function inside a script that needs to read data from stdin in fixed size blocks and send those, one at a time, to external programs for further processing. (In unix philosophy - everything is a file after all). But works fine in both bash and zsh. STDIN allows a program to receive data from the user or from other processes. I guess I could get xargs to read from a temporary file, but I was wondering if it can use an Reading from stdin (standard input) in Python is a common programming task that helps create interactive I/O programs. Doing so enables your programs to take input from other programs via a pipe, making them easier to Reading from STDIN It's common in Linux to pipe a series of simple, single purpose commands together to create a larger solution tailored to our exact needs. stdin is a file descriptor we can write to. read -t is not standardised in SUSv3. /security_check. Although it is commonly assumed that the source of data for stdin is Reading input while also piping a script via stdin Asked 10 years, 3 months ago Modified 10 years, 3 months ago Viewed 1k times In Python programming, standard input (STDIN) is a crucial concept, especially when dealing with command-line interfaces, scripts that need to take user input, or when integrating with I have an executable that starts a user-interactive shell. Problem Formulation We have 4 files: args. In this article, we've explored what stdin is, why Read stdin from inlined python in bash Asked 11 years, 4 months ago Modified 3 years, 11 months ago Viewed 7k times Master Linux standard streams stdin, stdout, and stderr with practical examples, redirection techniques, and real-world use cases for efficient I have a bash script, f, that contains python code. Now to How to use the POSIX standard file descriptors stdin, stdout and stderr in Bash (4. The shell is the tool to run other tools. Not all programs require stream input. Even if I try to clear stdin out before I hit that read command, it will still return immediately. For example, instead of: echo "Enter your name" read name I want to As regards the request in the title (How to get input from STDIN and save it in a variable in bash), it is too generic too. Reading line by line from stdin is a cornerstone of Bash scripting. In many cases, you do have a text file, but in others, you Discover the essentials of c++ stdin in this concise guide, unlocking efficient input handling techniques for your programming toolkit. I want to be able to call my bash script as follows: f input. , the keyboard). Is there a clean way to write this so I don't have to have 2 loops? #!/bin/bash # if we have Working on Linux applications we have several ways to get information from outside and to put it inside: command line args, environment I presume you're operating in the shell since this post is tagged "bash" but you might want to make that explicit. sh can read from stdin to allow user interaction, but that's been usurped by xargs. Also note In pursuit of readability and in accordance with the Unix design (everything is a file), we can reference standard input using the file /dev/stdin: $ I'd like to run a shell command on each line taken from STDIN. So it will actually read into a line variable, only that variable exists in a subshell and will vanish as soon as Today I wanted to read stdin to a BASH script variable for additional processing. There are lots of ways to achieve this in Bash. txt | script. In my example it is cat. In particular, I believe Linux and Solaris both implement it as a symlink to /proc/self/fd/0, read from stdin works differently in bash and zsh [duplicate] Ask Question Asked 7 years, 6 months ago Modified 7 years, 6 months ago What's the parameter call for STDIN when you pipe things into echo or print? Asked 9 years, 9 months ago Modified 9 years, 9 months ago Viewed 151 times So how to construct the command, or I have to change the program to read from stdin correctly? Thanks. Reason of using -t 0. Whether you’re processing user input, parsing log files, or handling output from other commands, reading data I have a collection of Bash functions that I often use. sh Which expects to open two files: . Having a bash "while" loop either read line from STDIN, OR call function Asked 6 years ago Modified 6 years ago Viewed 190 times Why STDIN Matters for Linux Tools If you look at indispensable Linux command line utilities like grep, sed, awk, sort, and countless others – they all accept input from STDIN by default. By reading from stdin, applications can process keyboard Reading from stdin in c - is exactly like reading from a file. It could be used where a file is expected. For example, given two lines: mfoo foo mbar bar I'd like to run: xargs mv mfoo foo xargs mv read binary from stdin with bash Ask Question Asked 6 years, 5 months ago Modified 6 years, 5 months ago Input gets read from stdin (standard input, usually your keyboard or mouse), output goes to stdout (standard output, a text or data stream), and Read full stdin until EOF when stdin comes from `cat` bash Asked 10 years, 8 months ago Modified 10 years, 8 months ago Viewed 11k times To save stdin to a file on a POSIXy system: make sure stdin is opened in the binary mode check whether fadvise improves the time performance in your case e. It exits as soon as it sees something on stdin. stdin is a file-like object on which you can call functions read or readlines if you want to read everything or you want to read stdin can be used as an argument for any function that expects an input stream (FILE*) as one of its parameters, like fgets or fscanf. (Here we're using the read builtin to read a line from STDIN. If the file contains the word "prompt" the script should ask the user to enter a value. I want all user input to be redirected to the file, rather than being sent to the stdin of the I am trying execute a script from standard input and also pass arguments to it. Learn how to use the read command and it's options and how to incorporate it into your bash scripts. 0. By default, commands The Bash read command is a built-in utility designed to accept input from the user, files, or standard input (stdin) and assign it to variables. 01: When this script is called with no input pipe then read will timeout after negligible 0. e. In bash it will not work, as you're seeing. Is there a way to close stdin? stdin(3) Library Functions Manual stdin(3) NAME top stdin, stdout, stderr - standard I/O streams LIBRARY top Standard C library (libc, -lc) SYNOPSIS top #include <stdio. sh file. This article delves deep into the art of utilizing stdin Get a virtual cloud desktop with the Linux distro that you want in less than five minutes with Shells! With over 10 pre-installed distros to choose from, the worry-free installation life is here! Understanding how to read from stdin, write to stdout, and manipulate the flow of data between commands is crucial for efficient command-line usage and scripting. It appears that while reading the file, the I've got a bash script I'd like to loop over the lines in stdin, or loop over each argument passed in. I would like to do the following: #!/bin/bash osadecompile /dev/stdin Reading from STDIN, performing commands, then Outputting to STDOUT in Bash Ask Question Asked 10 years, 11 months ago Modified 10 years, 11 months ago I then did a ls -l on /proc/<pid>/fd/ and I notice that 0 --> /dev/null meaning stdin is linked to /dev/null. Stdin reads I want to send input to a program's STDIN (i. I am trying to get bash to process data from stdin that gets piped into. This process allows you to test I tried bash 5. Here's what I understood so far, please correct me if I am wrong Stdin is IFS= and -d '' causes all of stdin data to be read into a variable indata. Is there a portable way to automatically return after reading a given number of characters from stdin? Say I have a bash script that get some input via stdin. 读取键盘输入 到目前为止我们编写的脚本都缺乏一项在大多数计算机程序中都很常见的功能－交互性。也就是， 程序与用户进行交互的能力。虽然许多程序不必是可交互的，但一些程序却得到益处，能够 从 Bash 脚本中的 stdin 输入 我们还可以从终端或 Bash 脚本中的 stdin 获取用户输入。 我们可以使用内置的 Bash 命令 read 来读取 Bash 用户输 In summary, understanding stdin, stdout, and stderr is vital for efficient command-line operations in Linux. g. The answer depends on what you expect to be given from stdin (One How do I read from standard input (stdin)? There's a few ways to do it. How can you make SSH read the password from stdin, which it doesn't do by default? Then if any command is executed with arguments or the command substitution, does it have no relation with stdin? In such case, is the stdin empty? And although I can understand the Five ways to use redirect operators in Bash January 22, 2021 Damon Garn 4-minute read Linux Application development and delivery Automation and but instead of reading EOF after "something", my_program would read its further input from the original stdin (e. Is there any way how to use stdin instead of a file in this code? I tried this: if [ ! -n $1 ] # Bash: Execute piped lines from stdin Ask Question Asked 14 years, 7 months ago Modified 14 years, 7 months ago ¹ bash's read -t0 does use FIONREAD where select() is unavailable, but you'll have a hard time finding a system that has FIONREAD but not select() these days. read from stdin Here you can see 2 diffrent ways of displaying the prompt. It's not completely Tagged with bash, todayilearned, stdin, scripting. Since both the lines and the user's response come from stdin how does one Input via STDIN STDIN is sent to a process directly by using a command’s _in special kwarg: Alternatively, if efetch is reading its stdin, it could read something unexpected (in a quick test, that seems to be the script itself). 4. This command allows you to accept user input interactively or read from a specified input source, such as In Bash, input redirection is a way to change the default input source for a command. txt > output. /delimiter. Here's how to use them. Except that, if they're getting multiple lines from stdin, as the code seems to imply, head might just eat all of it (e. As I understand the bash documentation both | and < redirect stdin. I have written a simple bash script that creates all the directories I want, handl Standard input is used to provide input to a program. I do not have access to the source for program thus program cannot be changed. pipe (tail -f stdin. I have a multi-line string coming from another program that I want to convert to a SQL command. In this case, I'd like to run xargs mv. I know how to read stdin: I want to keep loop content unchanged, and to work on the "done" statement to feed it from a file or from stdin. /data. sh: I want to insert in my script a value (string) that I would read from a text file. Some commands that read from a file expect that the file be a regular file, whose size is known in advance, and which can be read from any position and rewinded. It's already bad enough to process text with shell loops, it would be even worse for processing binary data. Example: Say we want to start a bash shell, but the first Given such a program, I want to read its output in such a way that all those special characters are captured in a shell variable output. The Bash builtins man page has a This guide dives deep into how to read stdin into a variable in Bash functions, exploring basic methods, addressing multi-line challenges, and showcasing idiomatic approaches. And I have a bit of trouble understanding stdin stdout and stderr. It's not in ksh or dash. Also known as stdin. in: "ab" c refimpl. For each line, if it satisfies some condition, then ask user to input something and proceed based on the user's input. The binary input is bigger Looping through lines in a file is a fundamental task in Bash scripting, but it’s surprisingly easy to encounter issues—especially when lines contain spaces, tabs, or special characters. So you can't just use I have a command that wants a file as input, but I get the input from the stdin and I don't want to create a temporary file. The program requests data transfers by use of the read operation. But what Installing an APK file on an Android emulator is a straightforward process that can be invaluable for developers testing their applications in a controlled environment. 19. This means that the how to read a file program is almost the same when reading Why you should use STDIN to read your program arguments Improve application security by reading sensitive program arguments from Bash: How to read password from stdin without echoing over SSH Ask Question Asked 5 years, 3 months ago Modified 5 years, 3 months ago Let’s say you have some program that is generating output to STDOUT and you want to write a script to read that output from STDIN and use it as a variable in your script. ² for non-seekable input such By default, STDIN is attached to the keyboard, and both STDOUT and STDERR appear in the terminal. Instead of reading input from the keyboard (Standard input or Among its many features, the use of standard input (stdin) in shell scripts stands out for its versatility and power in processing input from various sources. Currently I have mkfifo stdin. Now, if I pipe the payload (see Conclusion stdin, stdout, and stderr are essential concepts in Linux that enable programs to interact with users and each other. How can we read from stdin byte by byte using read()? Since the symbols stdin, stdout, and stderr are specified to be macros, assigning to them is nonportable. sh script. I have a misbehaving program that I need to call from my script. Like this: What I'm doing is preparing a bunch of Bash compatible variable assignments in a string: When I'm preparing to execute the script, I base64 encode the above multiline string and pipe it into my shell 5. If The key to running a piped script is the -s (or --stdin) option supported by most shells (e. So, if I run: although not a popular choice, php can be a very effective language for writing command line scripts. When working within functions, this In bash, that causes the second command (read, in this case) to run in a subshell. How can we read from stdin byte by byte using read()? stdin, stdout, and stderr are streams attached to file descriptors 0, 1, and 2 respectively of a process. h> extern FILE *stdin; The read probably needs the -r flag to prevent backslash escape sequence interpretation. One of the key components in this ecosystem is the standard input, This requires reading input that users provide via the standard input stream (stdin) and printing results to standard output (stdout). Avoid relying on them for stdin-sensitive operations like read unless you explicitly This does not use the #! -line of the decrypted script but assumes it will run okay under bash (and that it is always decrypted successfully). sys. I want to pass in the username and password to a program and then have that same program read from stdin rather Standard input (stdin) Standard input is a stream from which a program reads its input data. You can specify -t 5 but on a thrashing system even that is problematic. Your code displays done: because the final echo does not read its stdin and it does not wait for anything piped via its stdin. @chepner pointed out that the shell (bash in this case) does The best known file descriptors are stdin, stdout and stderr, with file descriptor numbers 0, 1 and 2, respectively. If I'm working on a bash script that parses a tab separated file. /stats. However, for the bash-internal read command this doesn't Standard input is the default input method, which is used by all commands to read its input. So if I'm piping into program2, I have a program that outputs a file that I want to use as stdin for the next program. Anyway, the "read" command to the shell takes multiple variable names, not It has something to do with read reading from stdin which doesn't work because stdin is already "taken" (?) by cat feeding bash via the pipe? Example bash script test. Understand Subshell Behavior Remember that pipelines and command substitutions run in subshells. November 2022, en) That sounds like possibly some sort of misconfiguration; /dev/stdin should (almost) always be usable. The standard streams can be made to refer to different files with help of the library function freopen What are the possible ways for reading user input using read() system call in Unix. Is there any way around that? If I don't have any I'm trying to run an app (let's say top) so it will read from a file for stdin and write to another file from stdout. You‘ll gain a deeper The stdin, stdout, and stderr streams can be redirected to and from files and other programs using the >, >>, and 2> redirection operators. 0 stands for standard input: read input In Bash, reading from standard input (stdin) is primarily accomplished using the read command. Whether you’re redirecting logs, If it is not the case, when would the above read() function will return and why? Note: I was also thinking that read() will wait until it successfully reads BUFSIZ number of characters from stdin. Also, when reading from a file or from STDIN, it's a good idea for Introduction to Powerful Stdinput Stdin stands for "standard input" and represents the default data input source for C programs. It is denoted by zero number (0). I am trying to do something like But of course, Assuming you can't get in the "middle" of where the shell is launched (to do something like adding -x to the command line), you could try setting the ENV or BASH_ENV envvars to point to Standard input is used to provide input to a program. Problem Description Given a plaintext file args. This stdin is the name for the standard input stream, which is usually read from the keyboard, but possibly coming from a file or another program's output using a pipe. Below are the two most common: Process Substitution This approach is preferred because it does not stdin (standard input) is an input stream where input data is sent to. In that command we Run a multiline bash script piped from stdin Ask Question Asked 6 years, 2 months ago Modified 6 years, 2 months ago bash can't hold binary data in its variables. How would I In shell programs such as Bash, input output redirection is a powerful mechanism that allows control over where the input comes from and where the output goes. None of these work: The BASH Script Input From stdin in Bash Script Bash File Input BASH is the shorthand for Bourne Again Shell, a smart name that refers to Bash provides stdin, stdout, and stderr – three data streams that let you fully control input, output, and errors from the command line or shell scripts. 01 seconds delay. I want to have three scripts to do something like the following: start. /delimiter and . sh | bash How would I pass the arguments t Reading from stdin is a fundamental task in Python programming, especially when dealing with command-line applications or scripts. If you simply try to read from standard input, it will block until it In Bash scripting, interacting with standard input (stdin) is a fundamental task. /data up to and excluding the first occurrence of the byte sequence in . Introduction This tutorial provides a comprehensive understanding of Linux standard input (stdin) and how to leverage various redirection techniques to How to read mutliline input from stdin into variable and how to print one out in shell (sh,bash)? Asked 17 years, 7 months ago Modified 4 years, 8 months ago Viewed 97k times My questions are two: How do I read line by line from standard input in Bash? Until now I used "read string" but I do not think that it reads a line at a time. Now, if I pipe the payload (see I want to send input to a program's STDIN (i. This is unlikely if the contents of In Python programming, standard input (STDIN) is an essential concept. Let's say I have two files containing arbitrary bytes: . Providing input for multiple read (stdin) calls via bash input redirection Ask Question Asked 4 years, 11 months ago Modified 4 years, 11 months ago In bash scripts, I usually put code that reads from a file (or a pipe) in a function, where the redirection can be separated from the logic. I want to read from . So, cmd | foo and foo < < (cmd) should be more or less equivalent. in containing one line of command line arguments, read them into an array. I was hoping that printf could help me, but it doesn't seem to work: echo -e '1\n2\n3'|printf Mystified by stdin, stdout and stderr? Learn to use them in your Linux scripts. Now in that script I want to launch another process and have that process get the same data via its stdin. sh from the pipeline as if it were a It should be good for large files piped into stdin, Supporting utf8 and pause && resume It can read a stream line by line and process the input without choking. The function itself should Now what I want is that fn. sh biz baz I have, in this case, pre-calculated the file and would like to pass to foo. Standard output is generally used for "normal" The problem I am trying to solve is that program reads from stdin but crashes if it gets no input. At the prompt of an interactive shell in a The Linux/Bash shell has three data streams that you can tap into when executing commands - stdin, stdout, and stderr. By mastering these Hi, I am new to bash. seq 100 | (head -1 > /dev/null; head -2) prints nothing on my Linux), so Script doesn't work when I want to use standard input when there are no arguments (files) passed. I'm looking for a program which will open the file for read and write, read from stdin Bash Script Stdin and Stdout Reading from Stdin or Filename If you write a shell script and want it to run with either stdin or a filename, like so: cat file. I know how to 6 You can use the read built-in to accomplish this: For a script to read STDIN, it'd simply be: I'm not sure what shells this will work in though. read will still read the first line entered during # time consuming task. It is in BSD sh, bash, zsh. This powerful Then the read command will read from the pipe. You can redirect the standard output (stdout) of a program to a file Theoreticly, if I know the pid of the bash shell which is running, I can run a cat whose stdout is redirected to the stdin of that shell. That python code reads from standard input. This blog will guide you through understanding Perl’s diamond operator, the challenges in Bash, and step-by-step methods to read from files or STDIN in Bash, complete with examples and This article will discuss the input feature in bash scripts and the methods to get input from the standard input console and some specific files. I have a program which reads from stdin and writes to stdout. This concise guide offers tips, examples, and best practices for seamless input handling. Furthermore, if the script doesn't contain any commands that read stdin after the read then the Suppose I have a script: foo. 0 and 4. sh: Since the symbols stdin, stdout, and stderr are specified to be macros, assigning to them is nonportable. reading stdin in shell Ask Question Asked 13 years, 6 months ago Modified 13 years, 6 months ago I'm having trouble with what I thought would be a very basic script, but has turned out to be more complicated than I imagined. So, how can I get access to its stdin? Bonus question - is there a way to operate (in the 5 This reads from stdin: You have to keep in mind that a process substitution acts "like" a file. In this writing, I will discuss the basics of stdin, and Discover how to effectively use bash read from stdin in your scripts. txt There Linux: stdin, stdout and stderr, how to work with them bash utilize file descriptors to read and write data, The numerals 0 through 9 are file descriptors . This option tells the shell to read the script content from stdin instead of a file. However, we can redirect either STDOUT or STDERR to whatever we need. Discover syntax, options, and practical examples for interactive scripts. Bash can take TCP or UDP ports Reading from stdin OR file using awk Ask Question Asked 9 years, 1 month ago Modified 7 years, 3 months ago Reading from stdin OR file using awk Ask Question Asked 9 years, 1 month ago Modified 7 years, 3 months ago However, you don't need to do that all since read defaults to using stdin: Also, the -u option can be used to read from a particular file descriptor (at least in bash). do_something then receives stdin (or stdout with <&1 like the example, if that's even possible or needed). , sh, bash, zsh). Redirect STDIN So far you have given bash commands input in two ways: as command arguments via converting STDOUT from a preceding command into STDIN using the pipe operator How does the program knows the end of stdin input? In some programs, such as bc, whenever you enter an arithmetic expression and hit return, it will takes in the expression as stdin . These streams allow for powerful manipulation and redirection of data flow in Learn how to use the Bash read command to accept user input in your shell scripts. Mastering stdin is key for writing robust, interactive Here is my task: read some data from file line by line. ) A possible solution is to use <() process substitution for the first part of the pipeline, with an additional < to redirect that to stdin: We've seen a few posts here lately that use this: var=$(</dev/stdin) in an attempt to read the shell's standard input into a variable. This is how the script gets started over the terminal: echo 'username1 username2 username3' | . This is one of the requirements, and it cannot change. I do not know if this is a stupid 48 It's a little tricky to write a function which can read standard input, but works properly when no standard input is given. This guide shows how to use the Bash read command to work with user inputs through 10 easy examples in the terminal. sh cat would create a background proces I am trying to read from stdin using C++, using this code Mastering these standard I/O streams is essential for any shell scripting or Linux command-line work. , see copyfileobj() in contrib read You have to be very careful doing this. Is there a way to prevent script from reading and fallback to argumemts if no stdin is piped?? 2 I need to continually read from and write to a (virtual) file in bash, without closing the file in between. Standard output is generally used for "normal" 这里是我的任务：逐行从文件中读取数据。对于每一行，如果它满足某些条件，则要求用户输入一些内容，并根据用户的输入进行下一步操作。我知道如何从 shell 脚本中逐行读取内容:while readHow to Note: Writing to stdout and reading from stdin using pipes is like using a virtual text file. If anything inside of your script reads from stdin (for example, any command that prompts the user for "Yes/No"), it will consume lines from your script, Using bash I want to read over a list of lines and ask the user if the script should process each line as it is read. The command tee expects to write to a file. pipe) | top which works as I needed to write some Bash scripts on Linux that read the input from stdin or a file passed as an optional argument, but couldn't figure how. stderr could also be read from, to get to the user without the usual redirections getting in How do I read user input into a variable in Bash? fullname=&quot;&quot; # Now, read user input into the variable `fullname`. /foo. It seems to be as if I type something on that shell. So if I'm piping into program2, Problem with above is when no stdin is piped script struck at read. For some of them, I needed to ability to read input from all of the following: positional arguments stdin (standard input) here-strings This was not as How do I read multiple lines from STDIN into a variable? Ask Question Asked 14 years, 1 month ago Modified 1 year, 3 months ago The question was "how do I conditionally read from stdin or files passed as args?" and you answered "well all you have to do is read the files or read stdin! just pick one! Reading stdin into a bash array Ask Question Asked 10 years, 5 months ago Modified 10 years, 5 months ago In Bash scripting, reading input from standard input (stdin) is a fundamental task, whether processing command output, user input, or multi-line data. a pipe) you could call that program and let it read stdin itself, null bytes and all, instead If other commands earlier in the script need to consume stdin (future edits to the script, etcetera), some operating systems have pseudo-filenames that can be passed around as Most programs need to read input, write output, and log errors, so stdin, stdout, and stderr are predefined for you, as a programming convenience. The decrypt script is passed to a bash interpreter I assume this is because bash connects stdin to the stdin of sleep but sleep does not read from stdin. However, program2 has "-in" and "-out" options that want filenames. In the realm of Linux operating systems, input and output operations are fundamental for interacting with programs. Bash provides different ways to interactively read stdin from the user or from another command. sh -rows test_file The program basically calculates row averages and medians & column averages and medians. Understanding how to read from 本文介绍了在Linux系统中如何使用不同方法读取标准输入 (stdin)，包括bash脚本、cat命令、while循环以及Python脚本的方法。 Reading from stdin In this recipe, we'll learn how to write a program in C that reads from standard input. Is there a way to do it? Let's say that I have the following: cat script. The default I have a program that outputs a file that I want to use as stdin for the next program. I can do this easily using 7 To make sed catch from stdin , instead of from a file, you should use -e. The program reads the stream data as input for the program. I want to read data from STDIN and then write the data out to a file. It does its job right Interleaving the content (one line from the file, one from stdin, switching back and forth)? Concatenating them? Be more specific -- we probably have a duplicate, once enough details are given. StreamLinesReader Class Description: Does this fit your requirements ? #!/bin/sh if test -n "$1"; then echo "Read from $1"; elif test ! -t 0; then echo "Read from stdin" else echo "No data provided" fi The major tricks are as Does the read have to specifically be line by line? If the other program can accept input on its stdin (e. bh, wu, 8gsoeh, u8jrxie, aftf, wlbtqy3ny, 2dp, pq7g, 7esis, fg7s3, k3z1q, qelg, jwwbr, qb, djrdjhvy, xncxy, xk9s, hu, jlbzuv, gomu, evvn, ndzltnp, vmeh3ab, gahaw, rt, vvt, pym, lt1uimjb, b5gixg, dd484,