test -e file
[ -e file ]
[[ -e file ]]

x=2
test $x -eq 1
[ $x -eq 2 ]
[[ $x -eq 3 ]]

File Test Operators

File status can be examined using several operators.

Parameter:     Meaning
-s file     size greater than zero
-r file      exists and is readable
-w file      exists and is writable
-x file      exists and is executable
-u file      exists and has the SUID bit set
-g file       exists and has the SGID bit set
-k file      exists and has the SVTX sticky bit set
-e file       exists
-f file      exists and is an ordinary file
-d file      exists and is a directory
-c file      exists as a character special file
-b file      exists and is a named pipe file
-p file      exists and is a named pipe file
-L file      exists and is a symbolic link

-O file       file exists and its owner is the effective user id
-G file       file exists and its group is the effective group id
-S file       file exists as a socket special file

file1 -ef file2       file1 is another name for file2
file1 -nt file2       file1 is newer than file2
file1 -ot file2       file1 is older than file2
-t des       file descriptor des is open and associated with a terminal device

Numeric Expressions

For use with arithmetic

Expression        Result
exp1 -eq exp2      exp1 is equal to exp2
exp1 -ne exp2      exp1 is not equal to exp2
expl -lt exp2      exp1 is less than exp2
exp1 -le exp2      exp1 is less than or equal to exp2
exp1 -gt exp2      exp1 is greater than exp2
exp1 -ge exp2     exp1 is greater than or equal to exp2

String Expressions

While examining strings use the following
Parameter        Meaning
-n str      string is non-zero in length
-z str     string is zero in length
str1 = str2     str1 is the same as str2
str1 != str2     str1 is not the same as str2

[[ str = pattern ]]     str matches pattern
[[ str != pattern ]]      str does not match pattern
[[ str1 < str2 ]]     str1 is before str2 in the ASCII collation seq.
[[ str1 > str2 ]]     str1 is after str2 in the ASCII collation seq.
[[ -o opt ]]     option opt is on for this shell