CODEWITHSUNDEEP
bashshellsh
McCourt2364
McCourt2364

Reputation: 61

BASH Syntax Error - [: missing `]'

I am new to Bash programming and probably being really silly.

Basically I am writing a piece of script that will ping an IP Address I pass in, it will take from it packets transmitted and return an error or a pass message depending on the number of packets lost.

However whenever I run the script from my terminal I keep getting message -

./ipGatewayCheck.sh: line 13: [: missing]'`

This is my code:

#!/bin/bash

healthy_status=0

warning_status=10

critical_status=100

for gateway in $@

do
RESULT=`ping -q -c 10 $gateway | grep 'packets transmitted' | awk '{print $6}' | tr -d "%"`
echo "$RESULT"
if [ $RESULT -eq $healthy_status ]; then
  echo "No Issue - IP Address is pinging"
elif [ $RESULT -ge $warning_status && -le $critical_status ]; then
  echo "Warning - Issue with packet loss on this IP Address"
elif [ $RESULT -eq $critical_status ]; then
  echo "Critical - 100% packet loss on this IP Address"
fi

done

Any help would be greatly appreciated.

Upvotes: 2

Views: 1165

Answers (2)

Jonathan Leffler
Jonathan Leffler

Reputation: 754280

As diagnosed by anubhava in his answer, the problem is that the && operator terminates the test command leaving you with a [ without a matching ] and the error message you get.

There's an alternative fix — more traditional shell coding and portable to shells other than Bash. If you wish to use [, you have to use either the -a conjunction (instead of &&), or use two separate tests:

elif [ "$RESULT" -ge $warning_status -a "$RESULT" -le "$critical_status" ]; then

elif [ "$RESULT" -ge $warning_status ] && [ "$RESULT" -le "$critical_status" ]; then

Note that I had to add the second "$RESULT"; I also enclosed the variables inside double quotes to make sure there are no mishaps.

Upvotes: 3

anubhava
anubhava

Reputation: 785376

You need to use [[ and ]] in order to use && inside square brackets:

if [[ "$RESULT" -eq "$healthy_status" ]]; then
  echo "No Issue - IP Address is pinging"
elif [[ "$RESULT" -ge "$warning_status" && "$RESULT" -le "$critical_status" ]]; then
  echo "Warning - Issue with packet loss on this IP Address"
elif [[ "$RESULT" -eq "$critical_status" ]]; then
  echo "Critical - 100% packet loss on this IP Address"
fi

Alternatively you can also use (( and )) in BASH:

if (( RESULT == healthy_status )); then
  echo "No Issue - IP Address is pinging"
elif (( RESULT == warning_status && RESULT < critical_status )); then
  echo "Warning - Issue with packet loss on this IP Address"
elif (( RESULT == critical_status )); then
  echo "Critical - 100% packet loss on this IP Address"
fi

Upvotes: 5

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