'How to represent multiple conditions in a shell if statement?

I want to represent multiple conditions like this:

if [ ( $g -eq 1 -a "$c" = "123" ) -o ( $g -eq 2 -a "$c" = "456" ) ]   
then  
    echo abc;  
else  
    echo efg;   
fi

but when I execute the script, it shows

syntax error at line 15: `[' unexpected,

where line 15 is the one showing if ....

What is wrong with this condition? I guess something is wrong with the ().

bashshellunix


Solution 1:[1]

In Bash:

if [[ ( $g == 1 && $c == 123 ) || ( $g == 2 && $c == 456 ) ]]

Solution 2:[2]

Using /bin/bash the following will work:

if [ "$option" = "Y" ] || [ "$option" = "y" ]; then
    echo "Entered $option"
fi

Solution 3:[3]

Be careful if you have spaces in your string variables and you check for existence. Be sure to quote them properly.

if [ ! "${somepath}" ] || [ ! "${otherstring}" ] || [ ! "${barstring}" ] ; then

Solution 4:[4]

g=3
c=133
([ "$g$c" = "1123" ] || [ "$g$c" = "2456" ]) && echo "abc" || echo "efg"

Output:

efg

g=1
c=123
([ "$g$c" = "1123" ] || [ "$g$c" = "2456" ]) && echo "abc" || echo "efg"

Output:

abc

Solution 5:[5]

In Bash, you can use the following technique for string comparison

if [ $var OP "val" ]; then
    echo "statements"
fi

Example:

var="something"
if [ $var != "otherthing" ] && [ $var != "everything" ] && [ $var != "allthings" ]; then
    echo "this will be printed"
else
    echo "this will not be printed"
fi

Solution 6:[6]

#!/bin/bash

current_usage=$( df -h | grep 'gfsvg-gfslv' | awk {'print $5'} )
echo $current_usage
critical_usage=6%
warning_usage=3%

if [[ ${current_usage%?} -lt ${warning_usage%?} ]]; then
echo OK current usage is $current_usage
elif [[ ${current_usage%?} -ge ${warning_usage%?} ]] && [[ ${current_usage%?} -lt ${critical_usage%?} ]]; then
echo Warning $current_usage
else
echo Critical $current_usage
fi

Solution 7:[7]

You can also chain more than two conditions:

if [ \( "$1" = '--usage' \) -o \( "$1" = '' \) -o \( "$1" = '--help' \) ]
then
   printf "\033[2J";printf "\033[0;0H"
   cat << EOF_PRINT_USAGE

   $0 - Purpose: upsert qto http json data to postgres db

   USAGE EXAMPLE:

   $0 -a foo -a bar



EOF_PRINT_USAGE
   exit 1
fi

Sources

This article follows the attribution requirements of Stack Overflow and is licensed under CC BY-SA 3.0.

Source: Stack Overflow

Solution Source
Solution 1 Dennis Williamson
Solution 2 David Ferenczy Rogožan
Solution 3
Solution 4 Peter Mortensen
Solution 5 Peter Mortensen
Solution 6 Community
Solution 7 Peter Mortensen

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