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# 1  
Old 03-12-2020
Custom exit message according to flag

Hello everyone,

I'm currently working on a script that uses curl's to check internet connectivity with and without a proxy being specified.
Basically what I'd like to achieve is having the script output fail or success according to the "method" used (direct or via proxy).

A very ugly way of doing it:
Code:
 # "curl_args" contains "-x $2" and gets set if $2 exists
curl ${curl_args} "$1" &> /dev/null

if [ $? == 0 ]; then
   if [ "$#" == 1 ]; then
      printf "OK - able to connect to $1\n"
      exit 0
   elif [ "$#" == 2 ]; then
      printf "OK - able to connect to $1 from $2\n"
      exit 0
   fi
else
   if [ "$#" == 1 ]; then
      printf "CRITICAL - unable to connect to $1\n"
      exit 1
   elif [ "$#" == 2 ]; then
      printf "CRITICAL - unable to connect to $1 from $2\n"
      exit 1
   fi

The script expects 2x arguments. The first one is the URL and the second one is the proxy address.

Whats a more dynamic way of writing that ugly if statement?
# 2  
Old 03-12-2020
Id like to see the code for the commented line, because the code would be shorter.

Other than that sounds more lile homework to me.
Is it?
# 3  
Old 03-12-2020
no it's not homework.

I've made some changes to it (whole code as requested):

Code:
# if we specify a proxy on $2, add the -x flag to curl
if [ "$proxy" ]; then
  # the whitespace is important
  curl_args+=" -x $2"
  exit_msg+=" via $proxy"
fi

usage() {
  printf "$(basename $0) URL [proxy]\n"
  exit 0
}

exit_ok() {
  printf "OK - $1"
  exit 0
}

exit_fail() {
  printf "FAILED - $1"
  exit 1
}

curl_cmd="curl ${curl_args} $url"
case $# in
  1) $curl_cmd &>/dev/null && exit_ok "$exit_msg" || exit_fail "$exit_msg"
     ;;
  2) $curl_cmd &>/dev/null && exit_ok "$exit_msg" || exit_fail "$exit_msg"
     ;;
  *) usage
     ;;
esac

I'm currently trying to get rid of exit_ok() and exit_fail()

Last edited by da1; 03-12-2020 at 05:15 PM..
# 4  
Old 03-12-2020
I didnt request the whole code, just the first commented line.
Anyway, thanks.

First and foremost, both "${2:-}" are useless, as that would fill an empty variable with... emptyness.
Second, you dont want something in a variable that defines an extra option - if it hasnt been set by the user.

I'll keep the short approach you've had in the first post:
Code:
curl_args="--fail --max-time 3"


case ${#@} in
1)	url="$1"
	exit_msg="connecting to $url"
	;;
2)	url="$1"
	curl_args="$curl_args -x \"$2\""	# The 'inner' quotes needs escape so they are there when the variable is reused
	exit_msg="connecting to $url via $2"
	;;
esac

curl $curl_args "$url"
ret=$?

[[ 0 = $ret ]] && \
	exit_msg="SUCCESS - $exit_msg" || \
	exit_msg="FAILURE - $exit_msg"

echo "$exit_msg"
exit $ret

hth & hf

Last edited by sea; 03-12-2020 at 04:10 PM.. Reason: typo
# 5  
Old 03-12-2020
hmm, very interesting construct. thank you for that.

One question though regarding the following piece of code:
Code:
[[ 0 = $ret ]] && \
	exit_msg="SUCCESS - $exit_msg" || \
	exit_msg="FAILURE - $exit_msg"

Why not do a proper if/else statement here?

Quote:
First and foremost, both "${2:-}" are useless, as that would fill an empty variable with... emptyness.
I did that because of the "set -u". What would be the right approach?

Quote:
Second, you dont want something in a variable that defines an extra option - if it hasnt been set by the user.
Ok, can you elabortate on that? Why is it wrong (?) to append a string to a variable?
# 6  
Old 03-12-2020
You're welcome.

Quote:
Originally Posted by da1
One question though regarding the following piece of code:
Code:
[[ 0 = $ret ]] && \
	exit_msg="SUCCESS - $exit_msg" || \
	exit_msg="FAILURE - $exit_msg"

Why not do a proper if/else statement here?
It's shorter and i'm lazy.
Also it only 'contains' 1 task per situation, so this is enough.
However, if there are more lines to be made for each situation, i'd go with a proper if/else statement as well.

Quote:
Originally Posted by da1
I did that because of the "set -u". What would be the right approach?
Ok, can you elabortate on that? Why is it wrong (?) to append a string to a variable?
If you want to check wether a variable exists (or has content) or not (empty) and DECIDE what to execute according to that, it's a bad choice to fill the variables anway.

One usualy uses this to make sure a REQUIRED variable gets it's DEFAULT or FALLBACK values, as in:
Code:
var=${1:-default-value}

I have.. uhm.. misspelled.. my... uhm.. concern... in the previous post, because:
${1:-} doesnt actualy do something, and is basicly the same as ${1}, but it (the first one) indicates that you wanted to put some variable there, which then might interfere.
Also, by setting a string to an empty variable, you'd say the script to ALWAYS use '$proxy', because '$proxy' would contain something. (well, not in your actual code, that's just bad syntax)

The set -u only requires you to declare the variable before invoking it.
So any of these are valid options for that case/command:
Quote:
declare var
local var
var=""
hth

--- Post updated at 21:54 ---

On a further note, your exit codes in those functions just exit the fuction, therefor return could be used there.

For example, try this:
Code:
my_msg(){ echo "${1:-some string i dont care} ; return 1 ; }
my_msg
ret=$?
echo $ret
exit $ret

And then change the return number.

Hth
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