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 Car.java $ file -i CarDriver.java
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
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
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 encoding.sh as follows:
#!/bin/bash
#enter input encoding here
FROM_ENCODING="value_here"
#output encoding(UTF-8)
TO_ENCODING="UTF-8"
#convert
CONVERT=" iconv -f $FROM_ENCODING -t $TO_ENCODING"
#loop to convert multiple files
for file in *.txt; do
$CONVERT "$file" -o "${file%.txt}.utf8.converted"
done
exit 0
Save the file, then make the script executable. Run it from the directory where your files (*.txt) are located.
$ chmod +x encoding.sh $ ./encoding.sh
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
