Can linux cat command be used for writing text to file?
This doesn’t work for me, but also doesn’t throw any errors. Specifically interested in a cat -based solution (not vim/vi/emacs, etc.). All examples online show cat used in conjunction with file inputs, not raw text.
14 Answers 14
echo "Some text here." > myfile.txt If you need to use double quotes in your text, encompass the whole thing in single quotes. This is useful for .json and the likes, e.g. echo ‘<"info1": "123456">‘ > info.json
Sounds like you’re looking for a Here document
cat > outfile.txt some text >to save >EOF The > characters represent the default value of $PS2 ; they show up automatically, and are not meant to be typed. If you have a different value for $PS2 , that will show up instead.
cat > outfile.txt >Enter text >to save press ctrl-d I use the following code to write raw text to files, to update my CPU-settings. Hope this helps out! Script:
#!/bin/sh cat > /sys/devices/system/cpu/cpu0/cpufreq/scaling_governor /sys/devices/system/cpu/cpu1/cpufreq/scaling_governor This writes the text "performance" to the two files mentioned in the script above. This example overwrite old data in files.
This code is saved as a file (cpu_update.sh) and to make it executable run:
After that, you can run the script with:
IF you do not want to overwrite the old data in the file, switch out
cat > /sys/devices/system/cpu/cpu1/cpufreq/scaling_governor cat >> /sys/devices/system/cpu/cpu1/cpufreq/scaling_governor This will append your text to the end of the file without removing what other data already is in the file.
Writing Text to File Using Linux Cat Command
The Linux cat command is a powerful utility that allows users to concatenate, view and create files. One of its useful features is the ability to write text to a file, either by appending it to the end of the file or by overwriting the existing content of the file. In this article, we'll explore how to use the cat command to write text to a file in Linux, covering the various options and flags that can be used to customize the behavior of the command.
Introduction to the Linux Cat Command
The cat command is a simple yet versatile command that is commonly used in Linux to perform various file operations. It's short for "concatenate" and can be used to join multiple files together or to display the contents of a file on the screen.
The basic syntax of the cat command is as follows −
The options argument is optional and specifies various flags that modify the behavior of the cat command. The file argument is the name of the file you want to manipulate. If you don't specify a file, cat will read from standard input (for example, keyboard input). Here are some common examples of using the cat command −
To view the contents of a file on screen −
To concatenate multiple files and display the resulting result on the screen −
$ cat file1.txt file2.txt file3.txt
To concatenate multiple files and save the resulting output to a new file −
$ cat file1.txt file2.txt file3.txt > newfile.txt
As you can see, the cat command is a useful tool for viewing and manipulating text files in Linux. In the next section, we will look at how to use the cat command to write text to a file.
Write Text to a File Using the Cat Command
To write text to a file using the cat command, you can use the echo command to output the text and pipe it to the cat command. The echo command is a built-in shell command used to display a message on the screen or to write a message to a file.
Here's an example of using the echo and cat commands to write "Hello world!" in a new file called hello.txt −
$ echo "Hello, World!" | cat > hello.txt
The echo command outputs the string "Hello, World!", and the | The symbol (called "pipe") redirects the output of the echo command to the input of the cat command. The > prompt redirects the output of the cat command to the hello.txt file, overwriting the file if it already exists or creating a new file if it doesn't exist.
You can also use the echo and cat commands to add text to the end of an existing file. To do this, you can use the “>>” symbol instead of the > symbol.
For example, to add the text "This is a new line" to the end of the “hello.txt” file, you could use the following command −
$ echo "This is a new line" | cat >> hello.txt
Here is the output you would see if you ran this command −
Hello, World! This is a new line
You can also use the -n flag with the echo command to suppress the newline character at the end of the output. This can be useful if you want to write multiple lines to a file without adding extra blank lines between them.
For example, to write the following three lines to a file named “lines.txt” without adding any extra blank lines between them −
This is line 1. This is line 2. This is line 3.
You can use the following command −
$ echo -n "This is line 1." | cat > lines.txt $ echo -n "This is line 2." | cat >> lines.txt $ echo -n "This is line 3." | cat >> lines.txt
This will write the three lines to the “lines.txt” file as follows −
This is line 1.This is line 2.This is line 3.
You can also use the cat command to directly write text to a file, without using the echo command. To do this, you can use the cat command in combination with the > or >> symbol and the
This is line 1. This is line 2. This is line 3.
You can use the following command −
Conclusion
In this article, we have seen how to use the cat command to write text to a file in Linux. The cat command is a powerful and versatile utility that can be used for a variety of tasks, including concatenating files, viewing file contents, and writing text to a file. Using the various switches and flags available with the cat command, you can customize its behavior to meet your specific needs.
Writing Text to File Using Linux Cat Command
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1. Overview
In this tutorial, we’ll look at how to write text into a file using the Linux cat command.
2. The cat Command
The cat command is a utility command in Linux. One of its most common usages is to print the content of a file onto the standard output stream. Other than that, the cat command also allows us to write some texts into a file.
3. The Syntax
Let’s take a look at the general syntax of the cat command:
First, OPTION is a list of flags we can apply to modify the command’s printing behavior, whereas FILE is a list of files we want the command to read.
From the documentation, we can see that if no value is passed for the FILE argument, the cat command will read from standard input. Similarly, it will behave the same when a dash “-” value is passed for the FILE argument. In combination with the Linux redirection operators, we can make the cat command listen to the standard input stream and redirect the content to a file.
4. Making cat Read From stdin
Let’s execute the cat command:
After we enter the command, we’ll see that the command will not return anything. This is because the cat command is now listening to the standard input.
Let’s try to enter some texts into the terminal:
cat This is a new line This is a new lineWe can see that whatever texts we’ve entered into the standard input stream will be echoed to the output stream by the cat command. Once we are done, we can terminate the command by pressing CTRL+D.
5. Writing to a File Using cat
To write to a file, we’ll make cat command listen to the input stream and then redirect the output of cat command into a file using the Linux redirection operators “>”.
Concretely, to write into a file using cat command, we enter this command into our terminal:
We’ll see that once again the terminal is waiting for our input.
However, this time it won’t echo the texts we’ve entered. This is because we’ve instructed the command to redirect the output to the file readme.txt instead of the standard output stream.
Let’s enter some texts into the terminal, followed by CTRL+D to terminate the command:
cat > readme.txt This is a readme file. This is a new line.The file readme.txt will now contain the two lines we’ve entered.
To verify our result, we can use the cat command once again:
cat readme.txt This is a readme file. This is a new line.Voila! We’ve written into a file using the cat command.
6. Appending Text to File Using cat
One thing we should note in the previous example is that it’ll always overwrite the file readme.txt.
If we want to append to an existing file, we can use the “>>” operator:
cat >> readme.txt This is an appended line.To verify that the last command has appended the file, we check the content of the file:
cat readme.txt This is a readme file. This is a new line. This is an appended line.There we have it. The line we enter is appended to the end of the file instead of replacing the entire document.
7. Here Document
It is also worth noting that the here document syntax can be used with the cat command:
EOF is a token that tells the cat command to terminate when it sees such a token in the subsequent lines.
The token can be any other value as long as it is distinct enough that it won’t appear in the input stream literal. Do note that both the starting and ending EOF tokens will not show up in the readme.txt file.
8. Conclusion
In this article, we’ve taken a look at the general syntax of the cat command.
We’ve also shown how we can make cat command listen from standard input stream instead of a specific file.
Finally, we’ve demonstrated how to write or append to a file, using the cat command along with the Linux redirection operators.