Shell conditional judgment statement

a string judgment

 

 

Two actual combat

[root@localhost ~]# name=fengji

[root@localhost ~]# [ -z $name ] && echo yes || echo no

no

[root@localhost ~]# name=""

[root@localhost ~]# [ -z $name ] && echo yes || echo no

yes

[root@localhost ~]# aa=11

[root@localhost ~]# bb=22

[root@localhost ~]# [ "$aa" == "$bb" ] && echo yes || echo no

no

[root@localhost ~]# [ "$aa" -eq "$bb" ] && echo yes || echo no

no

[root@localhost ~]# aa=22

[root@localhost ~]# [ "$aa" -eq "$bb" ] && echo yes || echo no

yes

[root@localhost ~]# [ "$aa" == "$bb" ] && echo yes || echo no

yes

 

Three multiple conditional judgments

 

 

Four actual combat

[root@localhost ~]# aa=22

[root@localhost ~]# [ -n "$aa" -a "$aa" -gt 33 ] && echo yes || echo no

no

[root@localhost ~]# [ -n "$aa" -a "$aa" -gt 3 ] && echo yes || echo no

yes