tr [options] set1 [set2]
The options of tr command are:
◒ -c : complements the set of characters in string.
◒ -d : deletes the characters in set1
◒ -s : replaces repeated characters listed in the set1 with single occurrence
◒ -t : truncates set1
Tr command Examples:
1. Convert lower case letters to upper case
The following tr command translates the lower case letters to capital letters in the give string:
> echo "linux dedicated server" | tr "[:lower:]" "[:upper:]"
LINUX DEDICATED SERVER
> echo "linux dedicated server" | tr "[a-z]" "[A-Z]"
LINUX DEDICATED SERVER
2. Transform upper case letters to lower case.
Similar to the above example, you can translate the uppercase letters to small letters.
> echo "UNIX DEDICATED SERVER" | tr "[:upper:]" "[:lower:]"
unix dedicated server
> echo "UNIX DEDICATED SERVER" | tr "[A-Z]" "[a-z]"
unix dedicated server
3. Replace non-matching characters.
The -c option is used to replace the non-matching characters with another set of characters.
> echo "unix" | tr -c "u" "a"
uaaa
4. Delete non-printable characters
The -d option can be used to delete characters. The following example deletes all the non-printable characters from a file.
> tr -cd "[:print:]" < filename
5. Squeezing characters
You can squeeze more than one occurrence of continuous characters with single occurrence. The following example squeezes two or more successive blank spaces into a single space.
> echo "linux server" | tr -s " "
linux server
Here you can replace the space character with any other character by specifying in set2.
> "linux server" | tr -s " " ","
linux,server
6. Delete characters
The following example removes the word linux from the string.
> echo "linuxserver" | tr -d "linux"
server
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