Often you may want to use sed to convert all characters in a string to lowercase.
You can use the following basic syntax to do so:
sed -e 's/.*/\L&/' cities.txt
This particular example will convert each character in each line of the file named cities.txt to lowercase.
Here is what the various sed commands do:
- s/: Used to replace a specific pattern with another pattern
- .*: Used to specify that all characters in each line should be replaced
- \L&: Used to specify that all characters in lowercase from each line should be used as replacements
The following example shows how to use this syntax in practice.
Example: How to Use sed to Convert All Characters to Lowercase
Suppose we have a file named cities.txt that contains the names of various U.S. cities:
Suppose that we would like to convert all of the characters in each city names to lowercase.
We can use the following syntax to do so:
sed -e 's/.*/\L&/' cities.txt
The following screenshot shows how to use this syntax in practice:
Notice that this returns each city name in all lowercase letters.
Note that we could also use the > command to save these results to a new file named cities_new.txt:
sed -e 's/.*/\L&/' cities.txt > cities_new.txt
The following screenshot shows how to use this syntax in practice:
Notice that when we use the cat command to view the contents of cities_new.txt that each city name in the file is shown in all lowercase letters.
Related Tutorials
The following tutorials explain how to perform other common tasks in sed:
How to Use sed to Replace All Text After Match
How to Use sed to Replace All Text Before Match
How to Use sed to Extract All Lines Containing a Pattern
