conditional binary operator expected in shell script

I was trying a simple program to compare the string values stored on a log file and was getting an error as below,

#!/bin/bash
check_val1="successful"
check_val2="completed"
log="/compile.log"
if [[ grep $check_val1 $log -ne $check_val1 || grep $check_val2 $log -ne $check_val2 ]];
then echo "No Error"
else echo "Error"
fi
Error:
./simple.sh: line 7: conditional binary operator expected
./simple.sh: line 7: syntax error near `$check_val1'
./simple.sh: line 7: `if [[ grep $check_val1 $log -ne $check_val1 || grep $check_val2 $log -ne $check_val2 ]];'

2 Answers

Problem is in your if [[...]] expression where you are using 2 grep commands without using command substitution i.e. $(grep 'pattern' file).

However instead of:

if [[ grep $check_val1 $log -ne $check_val1 || grep $check_val2 $log -ne $check_val2 ]]; then

You can use grep -q:

if grep -q -e "$check_val1" -e "$check_val2" "$log"; then

As per man grep:

-q, --quiet, --silent Quiet mode: suppress normal output. grep will only search a file until a match has been found, making searches potentially less expensive.

[[ trigers the test command. Test doesn't support testing the exit status of a command just by typing the command