The humble <DEL> and other editing keys

[Randall R Schulz]

David,

Key sequence generation is not a shell issue, it's defined by the 
terminal emulator which gets key-codes from the OS and generates 
sequences of bytes to send through a pseudo-tty to whatever application 
(shell or otherwise) that's reading. Likewise, it interprets things 
like cursor-addressing or color-changing sequences written by 
user-level (controlling side of the pseudo-tty) and then issues 
appropriate system or library calls to produce the requested display effects.

Generally, terminal emulators pick a commercial terminal product (if 
such things still exist) or simply use the ANSI terminal control 
standard and implement the sequences defined by that product or standard.

I usually use "od -c" to discover what a key is sending under a 
particular terminal emulator.

My "~/.inputrc" file shows where the Cygwin console and Cygwin RXVT 
differ for the Fn keys and the six keys in the Insert-PageDown cluster 
above the arrow keys. Fortunately, there's no conflict between the two:

# Console:
#   F1 - F5
"\M-[[A"    "fg %1\C-M"
"\M-[[B"    "fg %2\C-M"
"\M-[[C"    "fg %3\C-M"
"\M-[[D"    "fg %4\C-M"
"\M-[[E"    "fg %5\C-M"


# RXVT:
#   F1 - F5
"\M-[11~"   "fg %1\C-M"
"\M-[12~"   "fg %2\C-M"
"\M-[13~"   "fg %3\C-M"
"\M-[14~"   "fg %4\C-M"
"\M-[15~"   "fg %5\C-M"


# Both Console and RXVT:
#   F6 - F12
"\M-[17~"   "fg %6\C-M"
"\M-[18~"   "fg %7\C-M"
"\M-[19~"   "fg %8\C-M"
"\M-[20~"   "fg %9\C-M"
"\M-[21~"   "fg %10\C-M"
"\M-[23~"   "fg %11\C-M"
"\M-[24~"   "fg %-\C-M"


# Console:
     "\M-[1~":   beginning-of-line       # Home
     "\M-[4~":   end-of-line             # End


# RXVT:
     "\M-[7~":   beginning-of-line       # Home
     "\M-[8~":   end-of-line             # End


# Both Console and RXVT:
     "\M-[2~":   paste-from-clipboard    # Insert
#   "\M-[5~"                            # Page-Up
     "\M-[3~":   delete-char             # Delete
#   "\M-[6~"                            # Page-Down


Randall Schulz


At 23:31 2003-02-14, David Christensen wrote:
>Elfyn McBratney wrote on 14 Feb 2003 18:18:47 -0000
> > In bash you can add the following
> >
> > # DEL key in bash
> > "\e[3~": delete-char
> >
> > to your ~/.inputrc or your /etc/inputrc file to get a functioning DEL
> > ke.
>
>Thanks!  I've been wondering about that for far too long.  :-)
>
>
>BTW  I read the readline portion of "man bash" and was able to figure
>out the "~/.inputrc", "\e", ":", "delete-char" parts, but how did you
>figure out that the <Del> key maps to "[3~"?  Searching "man bash" and
>"man readline" for "[3~" and subsets didn't seem to do the trick, nor
>did "apropos escape" or Google "[3~"...
>
>
>TIA,
>
>David


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