Re: detect pipe

[Ray Andrews <rayandrews@eastlink.ca>]

On 2021-01-27 3:59 p.m., Bart Schaefer wrote:
> [[ -p /dev/fd/0 ]]
Nuts, using that it turns out that the issue is that my functions tend 
to be called via aliases:

     alias test2='noglob test1'

    test1 ()
    {
         if [[ -p /dev/fd/0 ]]; then
             echo "PIPES ARE AS BAD AS CIGARETTES"
             grep --color=always "$1"
         else
             echo "NO, THEY AREN'T"
             grep --color=always "$1" "$2"
         fi
    }


Testing it:

    $ . test; echo "Now is the time for all good men" | test1 'the time'
    PIPES ARE AS BAD AS CIGARETTES
    Now is the time for all good men

    $ . test; echo "Now is the time for all good men" | test2 'the time'
    NO, THEY AREN'T
    grep: : No such file or directory

    $ . test; test1 'the time' junk    # junk contains the same string
    NO, THEY AREN'T
    Now is the time for all good men

    $ . test; test2 'the time' junk
    NO, THEY AREN'T
    Now is the time for all good men

... so the pipe test is fooled by the alias. Strange tho that it used to 
work and still does *sometimes*.  Very flaky. Dunno why an alias would 
... well that's just it, I don't know.