(no subject)

[henman]

Subject: How to compare for control codes in a string
X-Mailer: MH-E 8.6+git; GNU Mailutils 3.16; Emacs 29.1
--------


I want to see if the 1st character in a string is a formfeed and then remove it.

I use the following script to check it

    if [[ $line[1] == '\f' ]]    # Check if the 1st character is a formfeed
        then tmpline=${line[@]:1}  # strip the ^f off
        fi

but it's not working.  How should it be checked?


Thank you.
---------

Re: How to compare for control codes in a string

[Bart Schaefer]

On Thu, Oct 12, 2023 at 11:39 AM henman <dhenman@gmail.com> wrote:
>
>     if [[ $line[1] == '\f' ]]    # Check if the 1st character is a formfeed

That's checking for the two literal characters backslash and f which
will never match a single character as in $line[1].  You probably
meant

     if [[ $line[1] == $'\f' ]]    # Check if the 1st character is a formfeed

Except with $'...', processing of \f \t \n etc. is not done as part of
string interpolation, though you might be fooled into thinking so
because it may instead be done by the print and echo commands.

>         then tmpline=${line[@]:1}  # strip the ^f off

The [@] there doesn't mean anything when $line is not an array, though
it's harmless.

Re:

[Pier Paolo Grassi]

[-- Attachment #1: Type: text/plain, Size: 546 bytes --]

Il giorno gio 12 ott 2023 alle 20:40 henman <dhenman@gmail.com> ha scritto:

> Subject: How to compare for control codes in a string
> X-Mailer: MH-E 8.6+git; GNU Mailutils 3.16; Emacs 29.1
> --------
>
>
> I want to see if the 1st character in a string is a formfeed and then
> remove it.
>
> I use the following script to check it
>
>     if [[ $line[1] == '\f' ]]    # Check if the 1st character is a formfeed
>         then tmpline=${line[@]:1}  # strip the ^f off
>         fi
>

hello, this should work:

if [[ $line[1] == $'\f' ]]

cheers

[-- Attachment #2: Type: text/html, Size: 1703 bytes --]