On Fri, Sep 24, 2010 at 03:22, Marc Herbert <marc.herb...@gmail.com> wrote:
>> On Thu, Sep 23, 2010 at 04:38:42PM -0500, Michael Witten wrote:
>>> This is also possible:
>>>
>>> [ -f "$file" ] && do_something
>
> Note that this style is not compatible with set -e
I was going to note that same caveat in my original email, as I had recalled
running into that issue. However, my recollection seemed to be contradicted
by the manual:
info bash 'Shell Builtin Commands' 'Modifying Shell Behavior' 'The Set
Builtin'
which states:
`-e'
Exit immediately if a pipeline (*note Pipelines::), which may
consist of a single simple command (*note Simple Commands::),
a subshell command enclosed in parentheses (*note Command
Grouping::), or one of the commands executed as part of a
command list enclosed by braces (*note Command Grouping::)
returns a non-zero status. The shell does not exit if the
command that fails is part of the command list immediately
following a `while' or `until' keyword, part of the test in
an `if' statement, part of any command executed in a `&&' or
`||' list except the command following the final `&&' or `||',
any command in a pipeline but the last, or if the command's
return status is being inverted with `!'. A trap on `ERR',
if set, is executed before the shell exits.
This option applies to the shell environment and each
subshell environment separately (*note Command Execution
Environment::), and may cause subshells to exit before
executing all the commands in the subshell.
Specifically:
The shell does not exit if the command that fails
is part of the command list immediately following a
`while' or `until' keyword, part of the test in an
`if' statement, part of any command executed in a
`&&' or `||' list except the command following the
final `&&' or `||', any command in a pipeline but
the last, or if the command's return status is being
inverted with `!'.
Even more specifically:
The shell does not exit if the command that fails is
... part of any command executed in a `&&' or `||'
list except the command following the final `&&' or
`||'...
For instance, the following script:
set -e
false && echo 0
echo 1
still echoes `1' when run with:
GNU bash, version 4.1.7(2)-release (i686-pc-linux-gnu)
Sincerely,
Michael Witten
