Linux write to file new line

How to put a newline special character into a file using the echo command and redirection operator?

I would like to create a file by using the echo command and the redirection operator, the file should be made of a few lines.

I tried to include a newline by «\n» inside the string:

but this way no file with three lines is created but a file with only one line and the verbatim content of the string.

How can I create using only this command a file with several lines ?

5 Answers 5

You asked for using some syntax with the echo command:

(But consider also the other answer you got.)

The $’. ‘ construct expands embedded ANSI escape sequences.

What echo does with character escapes is implementation defined. In many implementations of echo (including most modern ones), the string passed is not examined for escapes at all by default.

With the echo provided by GNU bash (as a builtin), and some other echo variants, you can do something like the following:

However, it really sounds like you want printf , which is more legible to my eye, and more portable too (it has this feature defined by POSIX):

You also might consider using a here document:

Here are some other ways to create a multi-line file using the echo command:

where the second and third commands use the >> redirection operator, which causes the output of the command to be appended (added) to the file (which should already exist, by this point).

where the parentheses group the echo commands into one sub-process, which looks and acts like any single program that outputs multiple lines (like ls , for example).

A subtle variation on the above is

This is slightly more efficient than the second answer in that it doesn’t create a sub-process. However, the syntax is slightly trickier: note that you must have a space after the < and a semicolon before the >.

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Linux append text to end of file

You need to use the >> to append text to end of file. It is also useful to redirect and append/add line to end of file on Linux or Unix-like system.

How to redirect the output of the command or data to end of file

The procedure is as follows

1. Append text to end of file using echo command:
   echo ‘text here’ >> filename
2. Append command output to end of file:
   command-name >> filename

How to add lines to end of file in Linux

The >> is called as appending redirected output. Create the file if does not exists. For example, append some networking command to net.eth0.config.sh script:
echo ‘I=eth0’ >> net.eth0.config.sh
echo ‘ip link set $I up’ >> net.eth0.config.sh
echo ‘ip addr add 10.98.222.5/255.255.255.0 dev $I’ >> net.eth0.config.sh
echo ‘ip route add default via 10.98.222.1’ >> net.eth0.config.sh

You can also add data to other config files. Another option is to run command and append output to a file. Run data command at the terminal and append output to output.txt:
date >> output.txt
Execute ls command and append data to files.txt:
ls >> files.txt
To see files.txt use cat command:
cat files.txt
more files.txt
less files.txt

How to append standard output and standard error

The following sytax allows both the standard output (file descriptor 1) and the standard error output (file descriptor 2) to be appended to the file name. The format for appending standard output and standard error is:
echo ‘text’ &>>filename
command &>>filename
find . type d -name «*.projects» &>> list.txt
This is semantically equivalent to
echo ‘text’ >>fileNameHere 2>&1
command >>fileNameHere 2>&1
date >>data.txt 2>&1

For more info read redirection topic.

Append text when using sudo

Try the tee command:
echo ‘text’ | sudo tee -a my_file.txt
echo ‘104.20.186.5 www.cyberciti.biz’ | sudo tee -a /etc/hosts
Of coruse we can use following syntax to append text to end of file in Linux
sudo sh -c ‘echo my_text >> file1’
sudo — bash -c ‘echo «some data» >> /my/path/to/filename.txt’
The -c option passed to the bash/sh to run command using sudo.
See “how to append text to a file when using sudo command on Linux or Unix” for more info.

Conclusion – Append text to end of file on Unix

To append a new line to a text on Unix or Linux, try:

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How to add a newline to the end of a file?

Using version control systems I get annoyed at the noise when the diff says No newline at end of file .

So I was wondering: How to add a newline at the end of a file to get rid of those messages?

20 Answers 20

And alternatively for OS X sed :

This adds \n at the end of the file only if it doesn’t already end with a newline. So if you run it twice, it will not add another newline:

To recursively sanitize a project I use this oneliner:

git ls-files -z lists files in the repository. It takes an optional pattern as additional parameter which might be useful in some cases if you want to restrict the operation to certain files/directories. As an alternative, you could use find -print0 . or similar programs to list affected files — just make sure it emits NUL -delimited entries.

while IFS= read -rd » f; do . done iterates through the entries, safely handling filenames that include whitespace and/or newlines.

tail -c1 reads the last char from a file.

read -r _ exits with a nonzero exit status if a trailing newline is missing.

|| echo >> «$f» appends a newline to the file if the exit status of the previous command was nonzero.

so echo «» >> noeol-file should do the trick. (Or did you mean to ask for identifying these files and fixing them?)

edit removed the «» from echo «» >> foo (see @yuyichao’s comment) edit2 added the «» again (but see @Keith Thompson’s comment)

Another solution using ed . This solution only affect the last line and only if \n is missing:

It essentially works opening the file for editing through a script, the script is the single w command, that write the file back to disk. It is based on this sentence found in ed(1) man page:

A simple, portable, POSIX-compliant way to add an absent, final newline to a would be text file:

This approach does not need to read the entire file; it can simply seek to EOF and work from there.

This approach also does not need to create temp files behind your back (e.g. sed -i), so hardlinks aren’t affected.

echo appends a newline to the file only when the result of the command substitution is a non-empty string. Note that this can only happen if the file is not empty and the last byte is not a newline.

If the last byte of the file is a newline, tail returns it, then command substitution strips it; the result is an empty string. The -n test fails and echo does not run.

If the file is empty, the result of the command substitution is also an empty string, and again echo does not run. This is desirable, because an empty file is not an invalid text file, nor is it equivalent to a non-empty text file with an empty line.

Add newline regardless:

Here is a way to check if a newline exists at the end before adding one, by using Python:

The fastest solution is:

Is really fast.
On a medium size file seq 99999999 >file this takes miliseconds.
Other solutions take a long time:

Works in ash, bash, lksh, mksh, ksh93, attsh and zsh but not yash.

Does not change file timestamp if there is no need to add a newline.
All other solutions presented here change the timestamp of file.

All solutions above are valid POSIX.

If you need a solution portable to yash (and all other shells listed above), it may get a bit more complex:

The fastest way to test if the last byte of a file is a newline is to read only that last byte. That could be done with tail -c1 file . However, the simplistic way to test if the byte value is a new line, depending on the shell usual removal of a trailing new line inside a command expansion fails (for example) in yash, when the last character in the file is an UTF-8 value.

The correct, POSIX-compliant, all (reasonable) shells way to find if the last byte of a file is a new line is to use either xxd or hexdump:

Then, comparing the output of above to 0A will provide a robust test.
It is useful to avoid adding a new line to an otherwise empty file.
File that will fail to provide a last character of 0A , of course:

Short and sweet. This takes very little time as it just reads the the last byte (seek to EOF). It does not matter if the file is big. Then only add one byte if needed.

No temp files needed nor used. No hardlinks are affected.

If this test is run twice, it will not add another newline.

If you just want to quickly add a newline when processing some pipeline, use this:

it’s also POSIX compliant.

Then, of course, you can redirect it to a file.

Provided there are no nulls in input:

. would suffice to always only append a newline to the tail end of an infile if it didn’t have one already. And it need only read the input file through the one time to get it right.

At least in the GNU versions, simply grep » or awk 1 canonicalizes its input, adding a final newline if not already present. They do copy the file in the process, which takes time if large (but source shouldn’t be too large to read anyway?) and updates the modtime unless you do something like

(although that may be okay on a file you are checking-in because you modified it) and it loses hardlinks, nondefault permissions and ACLs etc unless you are even more careful.

Although it doesn’t directly answer the question, here is a related script I wrote to detect files which do not end in newline. It is very fast.

The perl script reads a list of (optionally sorted) file names from stdin and for every file it reads the last byte to determine if the file ends in a newline or not. It is very fast because it avoids reading the entire contents of each file. It outputs one line for each file it reads, prefixed with «error:» if some kind of error occurs, «empty:» if the file is empty (doesn’t end with newline!), «EOL:» («end of line») if the file ends with newline and «no EOL:» if the file doesn’t end with newline.

Note: the script doesn’t handle file names which contain newlines. If you’re on a GNU or BSD system, you could handle all possible file names by adding -print0 to find, -z to sort, and -0 to perl, like this:

Of course, you’d still have to come up with a way of encoding the file names with newlines in the output (left as an exercise for the reader).

The output could be filtered, if desired, to append a newline to those files which don’t have one, most simply with

Lack of a final newline can cause bugs in scripts since some versions of shell and other utilities will not properly handle a missing final newline when reading such a file.

In my experience, the lack of a final newline is caused by using various Windows utilities to edit files. I have never seen vim cause a missing final newline when editing a file, although it will report on such files.

Finally, there are much shorter (but slower) scripts which can loop over their file name inputs to print those files which do not end in newline, such as:

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How to create a file in Linux from terminal window? [closed]

Want to improve this question? Add details and clarify the problem by editing this post.

Closed last year .

What’s the easiest way to create a file in Linux terminal?

17 Answers 17

Depending on what you want the file to contain:

touch /path/to/file for an empty file

somecommand > /path/to/file for a file containing the output of some command.

nano /path/to/file or vi /path/to/file (or any other editor emacs,gedit etc )
It either opens the existing one for editing or creates & opens the empty file to enter, if it doesn’t exist

Create the file using cat

Now, just type whatever you want in the file:

CTRL-D to save and exit

There are several possible solutions:

Create an empty file

The echo version will work only if your version of echo supports the -n switch to suppress newlines. This is a non-standard addition. The other examples will all work in a POSIX shell.

Create a file containing a newline and nothing else

This is a valid «text file» because it ends in a newline.

Write text into a file

These are equivalent. The $EDITOR command assumes that you have an interactive text editor defined in the EDITOR environment variable and that you interactively enter equivalent text. The cat version presumes a literal newline after the \ and after each other line. Other than that these will all work in a POSIX shell.

Of course there are many other methods of writing and creating files, too.

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How to append multiple lines to a file

I am writing a bash script to look for a file if it doesn’t exist then create it and append this to it:

So «line then new line ‘tab’ then text» I think its a sensitive format. I know you can do this:

But it seems weird since its two lines. Is there a way to append that in this format:

10 Answers 10

If sudo (other user privileges) is needed to write to the file, use this:

Or, if it’s a literal tab that you want (rather than the four spaces in your question):

You can achieve the same effect with echo , but exactly how varies from implementation to implementation, whereas printf is constant.

Another approach is to use tee

A few choice lines from tee ‘s man page:

The tee utility copies standard input to standard output, making a copy in zero or more files.

-a — Append the output to the files rather than overwriting them.

Here is an example to append multiple lines in a file:

SED can append a line to the end of a file like so:

sed -i ‘$ a text to be inserted’ fileName.file
$ selects end of file, the a tells it to append, and after this comes the text that is to be inserted. Then of course the file name.

Does this approach have any added benefit than other solutions?
Yes, this approach has the added benefit of appending to any files return in a search, such as this: find . -name «*.html» -exec sed -i ‘$ a ‘ <> \;

I used the above example to insert the ending html tag that was missing on every html page within a number of directories.

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