find: missing argument to `-exec'

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Newsgroups:  comp.unix.shell
Date:        Tue, 05 Dec 2006 21:10:38 +0100

> I get "find: missing argument to `-exec'" for the following command but I
> don't know how to fix:
>
>  find /other/path ! -group grp -exec ln -s {} dest +

Most implementations of ` require it to immediately follow the {} Otherwise, use \; rather than `

Michael Tosch

find: missing argument to `-exec'

find /other/path ! -group grp -exec sh -c '
  exec ln -s "$@" dest' arg0 {} +

Stephane CHAZELAS

find: missing argument to `-exec'

> > find /other/path ! -group grp -exec sh -c '
> >   exec ln -s "$@" dest' arg0 {} +
>
> what the arg0 here for?

When using the -c option to the shell, the first argument after the command string is used as the shell's $0, and the remaining ones fill in $@. So you need a dummy argument to fill in $0.

A better question would be what the exec is for. Most shells automatically exec the last (in this case only) command, kind of like tail-call elimination in Scheme. Notice:

$ sh -c 'sleep 10; echo ok' &
[17] 32501

$ ps -p 32501
  PID TTY          TIME CMD
32501 pts/0    00:00:00 sh

barmar $ sh -c 'sleep 100' &
[1] 6370
barmar $ ps -p 6370
  PID  TT  STAT      TIME COMMAND
 6370  p1  S      0:00.02 sleep 100

Barry Margolin

find: missing argument to `-exec'

> A better question would be what the exec is for.  Most shells
> automatically exec the last (in this case only) command, kind of like
> tail-call elimination in Scheme.  Notice:

ash and pdksh based shells don't, AT&T ksh, bash and zsh based ones do.

If you've got traps set up, that optimisation becomes a bug, such as in AT&T ksh. bash and zsh know not to do that optimisation when there are traps.

Stephane CHAZELAS