I searched SO and found that to uppercase a string following would work
str="Some string" echo ${str^^} But I tried to do a similar thing on a command-line argument, which gave me the following error
#!/bin/bash ## Output echo ${1^^} ## line 3: ${1^^}: bad substitution echo {$1^^} ## No error, but output was still smaller case i.e. no effect How could we do this?
The syntax str^^ which you are trying is available from Bash 4.0 and above. Perhaps yours is an older version (or you ran the script with sh explicitly):
Try this:
str="Some string" printf '%s\n' "$str" | awk '{ print toupper($0) }' 
tr '[a-z]' [[A-Z]'. tr '[a-z]' '[A-Z]'. GNU bash, version 4.3.42(1)-release (x86_64-apple-darwin14.5.0), and I get the same error as OP, so I don't think this is available on any bash 4.0 and above as you say. printf doesn't accept options, so it's much more reliable and predictable given something like str="-n" (try echo "-n" or echo -- "-n" vs printf "%s\n" "-n"). echo "lowercase" | tr a-z A-Z Output:
LOWERCASE 
/ as in tr /a-z/ /A-Z/ before my edit: this just works because it replaces / by / but is useless: pubs.opengroup.org/onlinepubs/9699919799/utilities/tr.html There also exists the more obscure and less useful tr '[:lower:]' '[:upper:]'. Be careful with tr unless A-Z is all you use. For other locales even '[:lower:]' '[:upper:]' fails, only awk's toupper and bash (v4+) works:
$ str="abcåäö" $ echo "$str" | tr '/a-z/' '/A-Z/' ABCåäö $ echo "$str" | LC_ALL=sv_SE tr '[:lower:]' '[:upper:]' ABCåäö $ echo "$str" | awk '{print toupper($0)}' ABCÅÄÖ $ echo ${str^^} # Bash 4.0 and later ABCÅÄÖ $ STR="ABCÅÄÖ" $ echo ${STR,,} abcåäö 
tr '[:lower:]' '[:upper:]' is working now for your example on OS X at least (also with LC_ALL=sv_SE) tr and a few others. tr '[:lower:]' '[:upper:]' is meant to work on any letter that have an uppercase variant in the locale, not just A-Z (whatever A-Z means, does it include É, Æ?). You have the same problem with some implementations of awk with toupper(), such as mawk, the default awk on Ubuntu. Alternatively, you could switch to ksh or zsh which have had case conversion support for decades (long before bash's ${var^^} added in 4.0), though with a different syntax:
#! /bin/ksh - typeset -u upper="$1" printf '%s\n' "$upper" (also works with zsh; note that in pdksh/mksh, that only works for ASCII letters).
With zsh, you can also use the U parameter expansion flag or the csh style¹ u modifier:
#! /bin/zsh - printf '%s\n' "${(U)1}" "$1:u" POSIXLY, you can use:
awk -- 'BEGIN{print toupper(ARGV[1])}' "$1" There's also:
printf '%s\n' "$1" | tr '[:lower:]' '[:upper:]' But in a few implementations, including GNU tr, that only works for single-byte characters (so in UTF-8 locales, only on ASCII letters, not accented letters of the Latin alphabet, not ligatures, not letters from other alphabets that also have a concept of case such as the Greek or Cyrillic alphabets).
In practice, none of those work for characters that don't have a single-character uppercase version such as ffi whose uppercase is FFI or the German ß. perl's uc (upper case) would work for those:
$ perl -CSA -le 'print uc for @ARGV' -- groß suffix GROSS SUFFIX Here with -CLSA to specify that the Stdio streams and Arguments are meant to be encoded in UTF-8 as long as UTF-8 is the charmap used in the Locale.
¹ though that modifier specifically is originally from zsh, already there in 1.0 from 1990, copied by tcsh later in 1992 for 6.01.03.
Try quoting the string:
echo "${str^^}" If someone is still getting error trying ${str^^}, you can try python -c or perl It is likely because bash version is lower than 4.
But, so far bash 4 or over is working swiftly with the existing solution.
L2U="I will be upper" Using python -c in bash
python -c "print('$L2U'.upper())" I WILL BE UPPER Similarly it also can be used to capitalise with:
service="bootup.sh on home" python -c "print('$service'.capitalize())" Bootup.sh on home Using perl
echo $L2U | perl -ne 'print "\U$_"' I WILL BE UPPER python or perl here is a good idea, the fact that you embed the expansion of the shell variable in the code passed to those interpreters (in the python ones) make it a code injection vulnerability and is very bad practice. It may explain the downvotes you got. You also forgot the quotes around $L2U in the last one, and remember echo can't be used to output arbitrary data.
bash?