How to Convert Files to UTF-8 Encoding in Linux

In this guide, we will describe what character encoding and cover a few examples of converting files from one character encoding to another using a command line tool. Then finally, we will look at how to convert several files from any character set (charset) to UTF-8 encoding in Linux.

As you may probably have in mind already, a computer does not understand or store letters, numbers or anything else that we as humans can perceive except bits. A bit has only two possible values, that is either a 0 or 1, true or false, yes or no. Every other thing such as letters, numbers, images must be represented in bits for a computer to process.

In simple terms, character encoding is a way of informing a computer how to interpret raw zeroes and ones into actual characters, where a character is represented by set of numbers. When we type text in a file, the words and sentences we form are cooked-up from different characters, and characters are organized into a charset.

There are various encoding schemes out there such as ASCII, ANSI, Unicode among others. Below is an example of ASCII encoding.

Character  bits
A               01000001
B               01000010

In Linux, the iconv command line tool is used to convert text from one form of encoding to another.

You can check the encoding of a file using the file command, by using the -i or --mime flag which enables printing of mime type string as in the examples below:

$ file -i
$ file -i
Check File Encoding in Linux
Check File Encoding in Linux

The syntax for using iconv is as follows:

$ iconv option
$ iconv options -f from-encoding -t to-encoding inputfile(s) -o outputfile 

Where -f or --from-code means input encoding and -t or --to-encoding specifies output encoding.

To list all known coded character sets, run the command below:

$ iconv -l 
List Coded Charsets in Linux
List Coded Charsets in Linux

Convert Files from UTF-8 to ASCII Encoding

Next, we will learn how to convert from one encoding scheme to another. The command below converts from ISO-8859-1 to UTF-8 encoding.

Consider a file named input.file which contains the characters:

� � � �

Let us start by checking the encoding of the characters in the file and then view the file contents. Closely, we can convert all the characters to ASCII encoding.

After running the iconv command, we then check the contents of the output file and the new encoding of the characters as below.

$ file -i input.file
$ cat input.file 
$ iconv -f ISO-8859-1 -t UTF-8//TRANSLIT input.file -o out.file
$ cat out.file 
$ file -i out.file 
Convert UTF-8 to ASCII in Linux
Convert UTF-8 to ASCII in Linux

Note: In case the string //IGNORE is added to to-encoding, characters that can’t be converted and an error is displayed after conversion.

Again, supposing the string //TRANSLIT is added to to-encoding as in the example above (ASCII//TRANSLIT), characters being converted are transliterated as needed and if possible. Which implies in the event that a character can’t be represented in the target character set, it can be approximated through one or more similar looking characters.

Consequently, any character that can’t be transliterated and is not in target character set is replaced with a question mark (?) in the output.

Convert Multiple Files to UTF-8 Encoding

Coming back to our main topic, to convert multiple or all files in a directory to UTF-8 encoding, you can write a small shell script called as follows:

#enter input encoding here
#output encoding(UTF-8)
#loop to convert multiple files 
for  file  in  *.txt; do
     $CONVERT   "$file"   -o  "${file%.txt}.utf8.converted"
exit 0

Save the file, then make the script executable. Run it from the directory where your files (*.txt) are located.

$ chmod  +x
$ ./

Important: You can as well use this script for general conversion of multiple files from one given encoding to another, simply play around with the values of the FROM_ENCODING and TO_ENCODING variable, not forgetting the output file name "${file%.txt}.utf8.converted".

For more information, look through the iconv man page.

$ man iconv

To sum up this guide, understanding encoding and how to convert from one character encoding scheme to another is necessary knowledge for every computer user more so for programmers when it comes to dealing with text.

Lastly, you can get in touch with us by using the comment section below for any questions or feedback.

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Aaron Kili
Aaron Kili is a Linux and F.O.S.S enthusiast, an upcoming Linux SysAdmin, web developer, and currently a content creator for TecMint who loves working with computers and strongly believes in sharing knowledge.

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Leave a Reply
  1. Hi,

    While converting a csv file to UTF8, using the below command I am getting the error like:

    iconv: illegal input sequence at position 5857689

    Command :

    $ iconv -f ASCII -t UTF-8 EDMTradesFeed_20210428.csv -o EDMTradesFeed.csv

    What would have gone wrong here? Can you please help?


  2. Thanks for sharing it, Can you please suggest what should be done in case file size is huge, as the file size we are having this script is not working on resulted in dump file.

      • Hi Aaron,

        File is not that big, it is failing for number of records more than 700, and no of columns will be 5-7 and our file is having Latin America and Chinese data as well. We have done as below, Kindly suggest if we can discuss over google chat.

        Our Script 
        cd $SRCFILEDIR
        for f in *txt
        encoding=$(file -b --mime-encoding $f)
                if [ utf-8 != $encoding ] && [ us-ascii != $encoding ] && [ binary != $encoding ]; then
                        iconv -f $encoding -t utf-8 $f -o $f
                        echo $encoding

        We get below error :

        us-ascii -- converted successfully
        us-ascii -- converted successfully
        binary -- converted successfully
        ./ line 6:  1156 Bus error               (core dumped) iconv -f $encoding -t utf-8 $f -o $f
        ./ line 6:  1161 Bus error               (core dumped) iconv -f $encoding -t utf-8 $f -o $f
  3. I do not know why we must follow many step, type commands, to do a simple convert in Linux? because in windows only default notepad can change file encoding easily. I can say i do more and more time in Linux to do simple works that i do in windows.

    So i do and read all solution in the INTERNET (Thanks Google!)
    but the best and easily solution for this problem answered in ask Ubuntu forum :

    It using the Microsoft Visual Studio Code text editor to fix a simple file encoding

  4. This was a great help in converting a file originally saved with notepad using Baltic symbols (turns out it was encoded with ISO8859-13). Thank you for the valuable information!


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