If statement in Bash creates weird 0 file -

when run following command:

if [ $(vboxmanage list vms | grep -c "all-in-one-1.2.7-wizard") > 0 ];     echo 'yes' else      echo 'no' fi 

a 0 file created in current directory:

$ ll ... -rw-rw-r--  1 abc abc     0 nov 19 17:33 0 

any idea why happening?

you not doing integer comparison, redirecting output of command $() 0, file 0 name created.

also, current "resolution" of if-condition based on result of execution of condition. if successful, executes condition.

instead, use -gt (greater than):

if [ $(vboxmanage list vms | grep -c "all-in-one-1.2.7-wizard") -gt 0 ];                                                                  ^^     echo 'yes' else     echo 'no' fi 

you can make sure behaviour doing >7 or whatever , see file 7 (or whatever) gets created.

when else condition executed? if couldn't redirect:

$ [ $(ls /root) > 3 ] && echo "yes" || echo "no" ls: cannot open directory /root: permission denied no 

see numeric comparison list of possible integer comparisons.