xargs short-circuit

[Devin Teske]

> -----Original Message-----
> From: owner-freebsd-hackers at freebsd.org [mailto:owner-freebsd-
> hackers at freebsd.org] On Behalf Of Matthew Story
> Sent: Tuesday, February 14, 2012 10:35 AM
> To: freebsd-hackers at freebsd.org
> Subject: xargs short-circuit
> 
> After reading the man-page, and browsing around the internet for a minute,
> I was just wondering if there is an option in (any) xargs to short-circuit
> on first failure of [utility [arguments]].
> 
> e.g.
> 
> $ jot - 1 10 | xargs -e -n1 sh -c 'echo "$*"; echo exit 1' worker || echo $?
> 1
> 1
> 
> such that any non-0 exit code in a child process would cause xargs to stop
> processing.  seems like this would be a nice feature to have.
> 

You can achieve this quite easily with a sub-shell:

As a bourne-shell script:

#!/bin/sh
jot - 1 10 | ( while read ARG1 REST; do
	sh -c 'echo "$*"; exit 1' worker $ARG1 || exit $?
	shift 1
done )

Or interactively in sh/bash:

$ jot - 1 10 | ( while read ARG1 REST; do sh -c 'echo "$*"; exit 1' worker $ARG1
|| exit $?; shift 1;done )

Or interactively in csh/tcsh:

% jot - 1 10 | /bin/sh -c 'while read ARG1 REST; do sh -c '\''echo "$*"; exit
1'\'' worker $ARG1 || exit $?; shift 1; done'

-- 
Devin

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