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Top Forums Shell Programming and Scripting Strange behaviour with "set -e" and functions Post 302335454 by tokland on Sunday 19th of July 2009 12:00:44 PM
Old 07-19-2009
Strange behaviour with "set -e" and functions

Hi,

This seems to be a recurrent problem on mailing lists and bug reports, but I've been unable to find a solution. Let's imagine we have this bash script:

Code:
#!/bin/bash
set -e

fun() {
  echo "fun_start"
  test 1 = 2 
  echo "fun_end"
}

echo "main_start"
fun 
echo "main_end"

This outputs:

Code:
main_start
fun_start

Right, but now I want the script to continue if "fun" fails, so I protect it with a "||":

Code:
echo "main_start"
fun || echo "fun failed"
echo "main_end"

And that's what I get (!):

Code:
main_start
fun_start
fun_end
main_end

The function continues even though there has been an error and my conditional statement is not even run. It seems that "set -e" is being ignored inside the function. That seems very counterintuitive. The only solution I found was adding "|| return 1" to every "dangerous" call inside a function, but then what's the point of using set -e?

So, am I doing something wrong? is there any easy way to get this desired output?

Code:
main_start
fun_start
fun failed
main_end

thanks
 

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echo(1B)					     SunOS/BSD Compatibility Package Commands						  echo(1B)

NAME
echo - echo arguments to standard output SYNOPSIS
/usr/ucb/echo [-n] [argument] DESCRIPTION
echo writes its arguments, separated by BLANKs and terminated by a NEWLINE, to the standard output. echo is useful for producing diagnostics in command files and for sending known data into a pipe, and for displaying the contents of envi- ronment variables. For example, you can use echo to determine how many subdirectories below the root directory (/) is your current directory, as follows: o echo your current-working-directory's full pathname o pipe the output through tr to translate the path's embedded slash-characters into space-characters o pipe that output through wc -w for a count of the names in your path. example% /usr/bin/echo "echo $PWD | tr '/' ' ' | wc -w" See tr(1) and wc(1) for their functionality. The shells csh(1), ksh(1), and sh(1), each have an echo built-in command, which, by default, will have precedence, and will be invoked if the user calls echo without a full pathname. /usr/ucb/echo and csh's echo() have an -n option, but do not understand back-slashed escape characters. sh's echo(), ksh's echo(), and /usr/bin/echo, on the other hand, understand the black-slashed escape characters, and ksh's echo() also understands a as the audible bell character; however, these commands do not have an -n option. OPTIONS
-n Do not add the NEWLINE to the output. ATTRIBUTES
See attributes(5) for descriptions of the following attributes: +-----------------------------+-----------------------------+ | ATTRIBUTE TYPE | ATTRIBUTE VALUE | +-----------------------------+-----------------------------+ |Availability |SUNWscpu | +-----------------------------+-----------------------------+ SEE ALSO
csh(1), echo(1), ksh(1), sh(1), tr(1), wc(1), attributes(5) NOTES
The -n option is a transition aid for BSD applications, and may not be supported in future releases. SunOS 5.11 3 Aug 1994 echo(1B)
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