Re: Possible bug Bash v5.22.6/5.1.16

[Chet Ramey]

On 2/17/24 6:40 AM, John Larew wrote:
> This is a portion of a script that appears to be problematic. Each of these 
> attempts appear to be valid; none of them work.
> The issue is apparent with bash in both termux v0.118.0/5.22.6 and Ubuntu 
> v22.04.3 LTS/5.1.16  (see attached).

The clue is in the error message (and its subsequent variants):

fg: current: no such job

which means that there are no background jobs in the execution environment
where `fg' is executed.

The background job in constructs like

( sleep 15s; set -m; fg %+; exit) &
( sleep 15s; set -m; fg %%; exit) &

is in the parent shell's execution environment; the subshell has no
background jobs of its own.

In constructs like

( sleep 15s; set -m; fg $$; exit) &
( sleep 15s; set -m; fg $!; exit) &

`fg' doesn't take PID arguments. (The reason you get the `current' in the
error message is that $! expands to nothing if there haven't been any
background jobs created, and `fg' without arguments defaults to the current
job.)

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

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