[SOLVED] Please help with if statement.

ondoho · 03-30-2018, 06:05 AM

Quote:

Originally Posted by Keith Hedger

Been using this construct for years, just checked now with an unassignred var and you're right no error, guess the BASH dev finally fixed this! Wonder when?
UPDATE error thown when exp is not in quotes

Code:

keithhedger@LFSDev:~-> echo $var1
aaa
keithhedger@LFSDev:~-> echo $var2

keithhedger@LFSDev:~-> if [ $var1 = $var2 ];then echo "Success!"; fi
bash: [: aaa: unary operator expected

double brackets also help:

Code:

if [[ $var1 = $var2 ]];then echo "Success!"; fi

=> no error.
of course best coding practice demands to use both i guess.

jmgibson1981 · 04-02-2018, 10:52 AM

Code:

BASE="8"
if [ ${BASE} -eq 8 ]
then echo "octal"
fi

LIGHT="green"
if [ ${LIGHT} -eq "green" ]
then echo "go"
fi

You may find your code easier to read if you indent and change structure a bit. The above is difficult at best for me to understand. Most scripting I've seen is done in the following way for bash.

Code:

BASE=8
if [[ "$BASE" == 8 ]] ; then
  echo "octal"
fi

LIGHT=green
if [[ "$LIGHT" == green ]] ; then
  echo "go"
fi

Indentation makes things a world easier to read imo. Also semicolons with your then and do parts easier to again... imo. This is how pretty much every script I've ever seen is done.

BW-userx · 04-02-2018, 11:43 AM

Quote:

Originally Posted by jmgibson1981

Code:

BASE="8"
if [ ${BASE} -eq 8 ]
then echo "octal"
fi

LIGHT="green"
if [ ${LIGHT} -eq "green" ]
then echo "go"
fi

You may find your code easier to read if you indent and change structure a bit. The above is difficult at best for me to understand. Most scripting I've seen is done in the following way for bash.

Code:

BASE=8
if [[ "$BASE" == 8 ]] ; then
  echo "octal"
fi

LIGHT=green
if [[ "$LIGHT" == green ]] ; then
  echo "go"
fi

Indentation makes things a world easier to read imo. Also semicolons with your then and do parts easier to again... imo. This is how pretty much every script I've ever seen is done.

actually that first code was proper in comparisons which was changed. that might cause confusion as a result of it.

Code:

BASE=8
LIGHT=green

if [[ "$BASE" -eq '8' ]] ; 
then
  echo "octal"
fi


if [[ "$LIGHT" == "green" ]] ; 
then
  echo "go"
fi