How to convert lower case to upper case letters in a shell script/command -

How to convert lower case to upper case letters in a shell script/command
How to convert lower case to upper case letters in a shell script/command, convert lower case to upper case, convert upper case to lower case

Here are a few tricks that can help when one needs to convert lower case to upper case characters in a file or in the ouput of a command.

I will start with the following example file:

$ cat lower-upper-case.file
first lower case characters line
second lower case characters line
FIRST UPPER CASE CHARACTERS LINE
SECOND UPPER CASE CHARACTERS LINE

Cases

Convert lower case to upper case using tr

$ tr '[a-z]' '[A-Z]' < lower-upper-case.file
FIRST LOWER CASE CHARACTERS LINE
SECOND LOWER CASE CHARACTERS LINE
FIRST UPPER CASE CHARACTERS LINE
SECOND UPPER CASE CHARACTERS LINE

The above example translates all lower-case chars to upper-case and writes the output to standard output.

Instead of tr '[a-z]' '[A-Z]' one can choose to use tr "[:lower:]" "[:upper:]" as in the following example:

$ tr "[:lower:]" "[:upper:]" < lower-upper-case.file
FIRST LOWER CASE CHARACTERS LINE
SECOND LOWER CASE CHARACTERS LINE
FIRST UPPER CASE CHARACTERS LINE
SECOND UPPER CASE CHARACTERS LINE

Convert upper case to lower case using tr

$ tr '[A-Z]' '[a-z]' < lower-upper-case.file
first lower case characters line
second lower case characters line
first upper case characters line
second upper case characters line

and for the second example:

$ tr "[:upper:]" "[:lower:]" < lower-upper-case.file
first lower case characters line
second lower case characters line
first upper case characters line
second upper case characters line

Convert upper case to lower case using dd (conv=lcase)

$ dd if=./lower-upper-case.file of=./lower-upper-case.file2 conv=lcase
0+1 records in
0+1 records out
134 bytes transferred in 0.000103 secs (1301011 bytes/sec)
$ cat lower-upper-case.file2
first lower case characters line
second lower case characters line
first upper case characters line
second upper case characters line

Convert lower case to upper case using dd (conv=ucase)

$ dd if=./lower-upper-case.file of=./lower-upper-case.file2 conv=ucase
0+1 records in
0+1 records out
134 bytes transferred in 0.000103 secs (1301011 bytes/sec)
$ cat lower-upper-case.file2
FIRST LOWER CASE CHARACTERS LINE
SECOND LOWER CASE CHARACTERS LINE
FIRST UPPER CASE CHARACTERS LINE
SECOND UPPER CASE CHARACTERS LINE

Both methods are very handy, but I'd say that using tr helps better inside scripts. It can redirect the output to a second file and using in further activities.

I will also write a script for converting files & folders names from upper/lower case to lower/upper case .
How to switch lower case to upper case and upper case to lower case in a string

Bookmarks: Echo "How to convert lower case to upper case letters in a shell script/command" around:

-------------------advertising-----------------

2 comment(s) to How to convert lower case to upper case letters in a shell script/command: