My If else statement only enters the first one?

hayloiuy · 04-22-2011, 04:17 AM

Code:

#!/bin/bash


echo $1

if [ $1=="A" ];
	
	then echo 0 > Type.txt
else
	
	if [ $1=="B" ];
		then echo 1 > Type.txt
	else
		if [ $1=="C" ];
			then echo 2 > Type.txt
		else
			if [ $1=="D" ];
				
				then echo 3 > Type.txt
					
			else
				echo "Fail"
			fi
		fi
	fi
fi

My code seems to always think the first if statement is true. What is wrong?

unSpawn · 04-22-2011, 04:30 AM

If you run the script as 'bash -vx /path/to/script.sh' you can see all variables filled in etc, etc. Also note there's no need for nesting so:

Code:

if [ "$1" = "A" ]; then
        echo 0 > Type.txt
elif [ "$1" = "B" ]; then
        echo 1 > Type.txt
elif [ "$1" = "C" ]; then
        echo 2 > Type.txt
elif [ "$1" = "D" ]; then
        echo 3 > Type.txt
else
        echo "Fail"
fi

should do and you could alternatively use a case statement:

Code:

case "$1" in
A) echo 0 > Type.txt;;
B) echo 1 > Type.txt;;
C) echo 2 > Type.txt;;
D) echo 3 > Type.txt;;
*) echo "Fail";;
esac

Code:

function help() { echo "Bash scripting guides:
http://www.tldp.org/HOWTO/Bash-Prog-Intro-HOWTO.html 
http://www.tldp.org/LDP/Bash-Beginners-Guide/html/index.html 
http://www.gnu.org/software/bash/manual/html_node/index.html
http://www.grymoire.com/Unix/Sh.html
http://www.tldp.org/LDP/abs/html/ 
http://wooledge.org/mywiki/BashFAQ?action=show&redirect=BashFaq 
http://wooledge.org/mywiki/BashPitfalls"; }

MTK358 · 04-22-2011, 08:52 AM

Quote:

Originally Posted by hayloiuy

My code seems to always think the first if statement is true. What is wrong?

You didn't put spaces around the "=" sign.

It's not some kind of C-like expression, "[" is a command. You can put any other command after it, too.

The "[" command is basically the test command, but it requires the last argument to be "]". Read man test for more info.

http://mywiki.wooledge.org/BashPitfa..._.3D_d_.5D_.5D