Re: bash command alias has a problem in using brace.

2021-08-31 Thread Chet Ramey 

On 8/27/21 9:47 PM, Dale R. Worley wrote:

Hyunho Cho  writes:



but if i use alias then '>' prompt does not appear and default bash
prompt appears

bash$ alias myalias='{ cat <<\@ > foo ;} 2> /dev/null'
bash$ myalias
bash$ 111
bash$ 222  # bash$ prompt
bash$ @





I don't know the details, but it must have something to do with what
event triggers the reading of the here-document.  That event isn't the
execution of the command containing it, I don't think, but more like
when the here-document-redirection is parsed. 


This is substantially correct. When the parser goes and collects the body
of the here-document, it's still parsing the contents of the alias.

--
``The lyf so short, the craft so long to lerne.'' - Chaucer
 ``Ars longa, vita brevis'' - Hippocrates
Chet Ramey, UTech, CWRUc...@case.eduhttp://tiswww.cwru.edu/~chet/

Re: bash command alias has a problem in using brace.

2021-08-27 Thread Dale R. Worley 
Hyunho Cho  writes:
> If i enter a command line like below then '>' prompt appears for the
> input of here document.
>
> bash$ { cat <<\@ > foo ;} 2> /dev/null
>> 111
>> 222  # '>' prompt
>> @
>
>
> but if i use alias then '>' prompt does not appear and default bash
> prompt appears
>
> bash$ alias myalias='{ cat <<\@ > foo ;} 2> /dev/null'
> bash$ myalias
> bash$ 111
> bash$ 222  # bash$ prompt
> bash$ @
>
>
> this only occurs in brace
>
> bash$ alias myalias='( cat <<\@ > foo ) 2> /dev/null'
> bash$ myalias
>> 111
>> 222   # '>' prompt
>> @

I don't know the details, but it must have something to do with what
event triggers the reading of the here-document.  That event isn't the
execution of the command containing it, I don't think, but more like
when the here-document-redirection is parsed.  Note that in your first
example, << is parsed after you type RET.  In the second two, the << is
inside quotes, and those characters are parsed only when "myalias" is
discovered in an input line and the alias definition is substituted for
it.

Dale

bash command alias has a problem in using brace.

2021-08-27 Thread Hyunho Cho 
Machine: x86_64
OS: linux-gnu
Compiler: gcc
Compilation CFLAGS: -g -O2 -flto=auto -ffat-lto-objects
-fstack-protector-strong -Wformat -Werror=format-security -Wall
uname output: Linux EliteBook 5.11.0-25-generic #27-Ubuntu SMP Fri Jul
9 23:06:29 UTC 2021 x86_64 x86_64 x86_64 GNU/Linux
Machine Type: x86_64-pc-linux-gnu

Bash Version: 5.1
Patch Level: 4
Release Status: release

###

If i enter a command line like below then '>' prompt appears for the
input of here document.

bash$ { cat <<\@ > foo ;} 2> /dev/null
> 111
> 222  # '>' prompt
> @


but if i use alias then '>' prompt does not appear and default bash
prompt appears

bash$ alias myalias='{ cat <<\@ > foo ;} 2> /dev/null'
bash$ myalias
bash$ 111
bash$ 222  # bash$ prompt
bash$ @


this only occurs in brace

bash$ alias myalias='( cat <<\@ > foo ) 2> /dev/null'
bash$ myalias
> 111
> 222   # '>' prompt
> @