Hi Randy,
On 12/28/2012 06:37 PM, Killen, Randy wrote:
Hello -
I encountered the situation shown below so thought that I would report it to
see if it might be a bug or is expected behavior. Please let me know if you
need additional information.
Randy
$
$ echo something | tr [:lower:] [:upper:]
SOMETHING
$ echo something | tr '[:lower:]' '[:upper:]'
SOMETHING
$
$ touch l
$ echo something | tr [:lower:] [:upper:]
tr: misaligned [:upper:] and/or [:lower:] construct
$ echo something | tr '[:lower:]' '[:upper:]'
SOMETHING
$ rm l
$
$ touch u
$ echo something | tr [:lower:] [:upper:]
tr: misaligned [:upper:] and/or [:lower:] construct
$ echo something | tr '[:lower:]' '[:upper:]'
SOMETHING
$ rm u
$
$ touch l
$ touch u
$ echo something | tr [:lower:] [:upper:]
something
$ echo something | tr '[:lower:]' '[:upper:]'
SOMETHING
$ rm l
$ rm u
This is expected behavior, caused by lack of quoting that results in the
shell (Bash) interpreting [...] as a wildcard pattern for file name
globbing (see glob(7)). If the 'nullglob' option of the shell is
disabled (use 'shopt nullglob' to display the current setting), a
wildcard that matches no files is kept as is. Thus the wildcards
[:lower:] and [:upper:] are either replaced by l resp. u if one of those
files exist or kept, if no matching file exists.
Quoting the special characters '[' and ']' by using '[:lower:]' resp.
'[:upper:]' (including the quotes) inhibits the shell from interpreting
them as file globbing wildcards. Therefore, you should always quote
character classes that are meant as arguments to a program.
HTH
Erik
