Re: why would "tr --complement --squeeze-repeats ..." append the substitution char once more? ...

[Albretch Mueller <lbrtchx@gmail.com>]

On 12/11/23, Greg Wooledge <greg@wooledge.org> wrote:
> Please tell us ...

 OK, here is what I did as a t-table

echo "abc123" > file.txt  # obvious text file
ftype=$(file --brief file.txt)  # got its type as reported by the "file" utility
echo "// __ \$ftype: |${ftype}|"
ftypelen=${#ftype}  # length of the string containing the file type
echo "// __ \$ftypelen: |${ftypelen}|"

# removing spaces et any other char which is not '[A-Za-z0-9.]'
replacing with underscores ...
# here is what I think to be an error happened instead of just
replacing ... by underscores
# it adds an underscore at the end?
ftype2=$(echo "${ftype}" | tr --complement --squeeze-repeats
'[A-Za-z0-9.]' '_');
echo "// __ \$ftype2: |${ftype2}|"
ftype2len=${#ftype2}
echo "// __ \$ftype2len: |${ftype2len}|"

the two strings are not the same length even though your are just
replacing ASCII characters, why did:
echo "${ftype}" | tr --complement --squeeze-repeats '[A-Za-z0-9.]' '_'
place a character at the end?
Probably echo and tr are not dancing well together. echo might be
tailgating an end of string character which tr then replaces with an
underscore.
which option do I use with echo for that not to happen?
SHould I probably play with IFS ...?

lbrtchx


On 12/11/23, Greg Wooledge <greg@wooledge.org> wrote:
> On Mon, Dec 11, 2023 at 02:53:07AM +0000, Albretch Mueller wrote:
>> echo "abc123" > file.txt
>> ftype=$(file --brief file.txt)
>> echo "// __ \$ftype: |${ftype}|"
>> ftypelen=${#ftype}
>> echo "// __ \$ftypelen: |${ftypelen}|"
>>
>> # removing spaces ...
>> ftype2=$(echo "${ftype}" | tr --complement --squeeze-repeats
>> '[A-Za-z0-9.]' '_');
>> echo "// __ \$ftype2: |${ftype2}|"
>> ftype2len=${#ftype2}
>> echo "// __ \$ftype2len: |${ftype2len}|"
>
> Please tell us:
>
>  * What you are trying to do.
>
>  * What you did (is the previous code all in a script?  if so, this is a
>    good answer for this part).
>
>  * What result you got.
>
>  * What you expected to get.