If I can do this in my bash shell:
$ STRING="A String"
$ echo ${STRING^^}
A STRING
How can I change my command line argument to upper case?
I tried:
GUARD=${1^^}
This line produces Bad substitution error for that line.
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Anthon
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user1135541
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3 Answers
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Let's start with this test script:
$ cat script.sh
GUARD=${1^^}
echo $GUARD
This works:
$ bash script.sh abc
ABC
This does not work:
$ sh script.sh abc
script.sh: 1: script.sh: Bad substitution
This is because, on my system, like most debian-like systems, the default shell, /bin/sh, is not bash. To get bash features, one needs to explicitly invoke bash.
The default shell on debian-like systems is dash. It was chosen not because of features but because of speed. It does not support ^^. To see what it supports, read man dash.
John1024
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4… and you can "explicitly invoke bash" for a script (i.e., specify that a script should be run by bash) by putting it in the "she-bang" (the first line of the script). `#!/bin/bash` will work on many systems, `#!/usr/bin/bash` will work on others, and `#!/usr/bin/env bash` should work on all systems that have bash (if it's in your search path). See [Does the shebang determine the shell which runs the script?](http://unix.stackexchange.com/q/87560/23408) and [Why is it better to use “#!/usr/bin/env NAME” instead of “#!/path/to/NAME” as my shebang?](http://unix.stackexchange.com/q/29608/23408) – Scott - Слава Україні Apr 13 '15 at 22:41
5
With tr command:
Script:
#!/bin/bash
echo $@ | tr '[a-z]' '[A-Z]'
Check:
$ bash myscript.sh abc 123 abc
ABC 123 ABC
Mandar Shinde
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