Bash – How to Uppercase Command Line Arguments

bashcase sensitivitystring

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

Tried

#!/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?

Best Answer

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) }'

NOTE

from man bash (parameter expansion) :

    ${parameter}
           The value of parameter is substituted.
 The braces are required when parameter is a positional parameter with
  more than one
digit, or when parameter is followed by a character which is not to be interpreted as part of its name.
* If the first character of parameter is an exclamation point (!), a level of variable indirection is introduced. Bash uses the value of the variable formed from the rest of parameter as the name of the variable; this variable is then expanded and that value is used in the rest of the substitution, rather than the value of parameter itself. This is known as indirect expansion. * The exceptions to this are the expansions of ${!prefix*} and ${!name[@]} described below. The exclamation point must immediately follow the left brace in order to introduce indirection.

Bash Strings – How to Compare Two Strings with Space

Change this line:

if [[ "$TEST" == "ON Master" ]];

To this:

if [ "$TEST" == "ON Master" ];

Details

The issue is the use of [[ .. ]]. The output is showing you the difference. Your value that you're getting for $STATUS is not simply "On Master". It most likely contains other characters, that are most likely not printable so are not being seen.

[[ .. ]]

++ echo On Master
+ TEST='On Master'
+ [[ On Master == \O\N\ \M\a\s\t\e\r ]]

[ .. ]

++ echo On Master
+ TEST='On Master'
+ '[' 'On Master' == 'ON Master' ']'

The use of double square brackets ([[ .. ]]) is discussed here on the TLDP Advanced Bash Scripting pages.

echo $STATUS

This line seems a little suspicious to me as well. I'd protect the contents of $STATUS by wrapping it in double quotes as well.

TEST=`echo "$STATUS"`

Also I'd drop the back ticks ( `...` ) and use the $( ... ) notation instead for executing this command. This change is just a best practice and isn't part of your issue though.

TEST=$(echo "$STATUS")

Control characters in output (^[[92mON^[[0m Master)

Given you're seeing these control characters in your output (^[[92m & ^[[0m) I'm suspicious that the grep command is introducing these into your output in the pipe. It may be that grep is aliases to always include the --color switch, I'd temporarily try calling the executable directly, and by pass any aliases that may be there. Just change the grep to this, /bin/grep.

The presence of these is what we suspected and is why the text was wrapping when you echo the variable $STATUS. These characters are unprintable, and change the color of the terminal to highlight matches that grep has found.

The presence of these also explains why the =~ operator didn't match too. You were trying to match 'On Master' with '^[[92mON^[[0m Master'.

Lastly the colored output with the control characters may be coming from another tool before the grep. I would need to see the actual output from /root/setup_ha to confirm this, but I would be suspicious of that tool as well in producing these characters in the pipe stream.

Stripping the control characters

I found this U&L Q&A titled: Program that passes STDIN to STDOUT with color codes stripped?.

Use either of these methods to get rid of the control characters.

Perl

$ cmd-with-colored-output | perl -pe 's/\e\[?.*?[\@-~]//g'

Sed

$ cmd-with-colored-output | sed -r "s/\x1B\[([0-9]{1,2}(;[0-9]{1,2})?)?[m|K]//g"