Re: [Help-bash] Reading and handling "control" characters from a file

[Davide Brini]

On Sat, 21 Apr 2012 14:13:52 -0400, Chet Ramey <address@hidden> wrote:

> On 4/19/12 6:11 PM, Conrad J. Sabatier wrote:
> > I've just started doing a little prototyping in bash for a program I'll 
> > eventually code most likely in C, and have hit a serious stumbling
> > block re: the handling of characters (bytes) in the very low range of
> > the ASCII table.
> 
> Bash variables are strings of characters.  There is a difference between
> a character with ASCII value 4 and a character with the ASCII value 52
> ("4").  Shell arithmetic convers the latter into numbers using the
> equivalent of strtol() before use.
> 
> To make what you want work, you'll have to figure out some way to offset
> the value you read from the file (i.e., c+'0') before attempting to use it
> in an arithmetic context.  Maybe perl or something like that could help.
> It's quite difficult to do using just what the shell provides.

Shouldn't the single quote trick work here? eg

$ a=$(printf '\x4\n')
$ printf "%d\n" "'$a"
4

-- 
D.