Re: bash usage.
- Date: Thu, 26 Oct 2017 18:05:51 -0400
- From: Jude DaShiell <jdashiel@xxxxxxxxx>
- Subject: Re: bash usage.
bash has a comments syntax to document what may not necessarily be clear with scripts. If I write a script at minimum just below the #!/usr/bin/env bash line I have a # file: line giving the file name followed by a dash and a little bit of a description what the script is supposed to do. Each to their own though, I just find that for me when I don't remember what a file does by its file name, I can search the two top lines using head -2 filename.sh and suddenly remember what I was trying to do with that script.
On Thu, 26 Oct 2017, David Margerison wrote:
Date: Thu, 26 Oct 2017 08:12:16 From: David Margerison <deltam@xxxxxxxxxxxxxxxxxxxx> To: "debian-user@xxxxxxxxxxxxxxxx" <debian-user@xxxxxxxxxxxxxxxx> Subject: Re: bash usage. Resent-Date: Thu, 26 Oct 2017 12:30:18 +0000 (UTC) Resent-From: debian-user@xxxxxxxxxxxxxxxx On 26 October 2017 at 21:59, Roberto C. S?nchez <roberto@xxxxxxxxxx> wrote:On Thu, Oct 26, 2017 at 04:19:42PM +1100, David Margerison wrote:On 26 October 2017 at 12:23, Roberto C. S?nchez <roberto@xxxxxxxxxx> wrote:mountpoint -q $WorkingDirectory if [[ $? = 0 ]]That will work, but is ridiculous considering this works by design: if mountpoint -q "$wd" ; then echo "$wd is a mountpoint" fiYes, quite right. Though, my syntax makes it clear that what is being tested/evlauated is the exit status, not the output. I know that the if evaluates the exit status, but that may not be immediately evident to someone who is not particularly familiar with shell programming.That's a fair point, but the documentation of the 'if' statement in 'man bash' will make that immediately clear to anyone who cares to read it. The [[ test, the $? parameter, and the =0 test are three separate redundancies that are not needed here to achieve the desired result. So the code you gave is a good illustration of how $? works, but should also be identified as a bad example of how to correctly achieve the goal in this case. Because in shell syntax, the 'if' statement is conceived and intended to be used directly with any/all commands. So I believe that good guidance should make that point clearly, and that is my reason for writing again here, to present that alternative. Also, some shells do not support [[ and its syntax differs from [ and 'test' in various fun ways.