namp10010/bash_test_operators.md

## bash_test_operators.md

      
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              bash_test_operators.md
            
          
    Bash test operators

A gist copied from kapeli page
Integer Comparison


Integer Comparison


-eq
is equal toif [ "$a" -eq "$b" ]


-ne
is not equal toif [ "$a" -ne "$b" ]


-gt
is greater thanif [ "$a" -gt "$b" ]


-ge
is greater than or equal toif [ "$a" -ge "$b" ]


-lt
is less thanif [ "$a" -lt "$b" ]


-le
is less than or equal toif [ "$a" -le "$b" ]


<
is less than(within double parentheses)(("$a" < "$b"))


<=
is less than or equal to(within double parentheses)(("$a" <= "$b"))


>
is greater than(within double parentheses)(("$a" > "$b"))


>=
is greater than or equal to(within double parentheses)(("$a" >= "$b"))


String Comparison


String Comparison


=
==
is equal toThe == comparison operator behaves differently within a double-brackets test than within single brackets.
[[ $a == z* ]]   # True if $a starts with an "z" (pattern matching).
 [[ $a == "z*" ]] # True if $a is equal to z* (literal matching).
 [ $a == z* ]     # File globbing and word splitting take place.
 [ "$a" == "z*" ] # True if $a is equal to z* (literal matching).


!=
is not equal toif [ "$a" != "$b" ]This operator uses pattern matching within a [[ ... ]] construct.


<
is less than, in ASCII alphabetical orderNote that the < needs to be escaped within a [ ] construct.if [[ "$a" < "$b" ]] if [ "$a" \< "$b" ]


>
is greater than, in ASCII alphabetical order.Note that the > needs to be escaped within a [ ] construct.if [[ "$a" > "$b" ]] if [ "$a" \> "$b" ]


-z
string is null that is, has zero length if [ -z "$s" ]


-n
string is not null.if [ -n "$s" ]


File Test Operators


File Test Operators


-e 
 -a
file exists-a is deprecated and its use is discouraged.


-f
file is a regular file (not a directory or device file)


-d
file is a directory


-h 
 -L
file is a symbolic link


-b
file is a block device


-c
file is a character device


-p
file is a pipe


-S
file is a socket


-s
file is not zero size


-t
file (descriptor) is associated with a terminal device
This test option may be used to check whether the stdin [ -t 0 ] or stdout [ -t 1 ] in a given script is a terminal.


-r
file has read permission (for the user running the test)


-w
file has write permission (for the user running the test)


-x
file has execute permission (for the user running the test)


-g
set-group-id (sgid) flag set on file or directory


-u
set-user-id (suid) flag set on file


-k
sticky bit set


-O
you are owner of file


-G
group-id of file same as yours


-N
file modified since it was last read


-nt
file f1 is newer than f2if [ "$f1" -nt "$f2" ]


-ot
file f1 is older than f2if [ "$f1" -ot "$f2" ]


-ef
files f1 and f2 are hard links to the same fileif [ "$f1" -ef "$f2" ]


!
"not" -- reverses the sense of the tests above (returns true if condition absent).


Compound Comparison


Compound Comparison


-a
logical andSimilar to &&


-o
logical orSimilar to `


References


https://kapeli.com/cheat_sheets/Bash_Test_Operators.docset/Contents/Resources/Documents/index
https://tldp.org/LDP/abs/html/tests.html
	Integer Comparison
`-eq`	is equal to`if [ "$a" -eq "$b" ]`
`-ne`	is not equal to`if [ "$a" -ne "$b" ]`
`-gt`	is greater than`if [ "$a" -gt "$b" ]`
`-ge`	is greater than or equal to`if [ "$a" -ge "$b" ]`
`-lt`	is less than`if [ "$a" -lt "$b" ]`
`-le`	is less than or equal to`if [ "$a" -le "$b" ]`
`<`	is less than(within double parentheses)`(("$a" < "$b"))`
`<=`	is less than or equal to(within double parentheses)`(("$a" <= "$b"))`
`>`	is greater than(within double parentheses)`(("$a" > "$b"))`
`>=`	is greater than or equal to(within double parentheses)`(("$a" >= "$b"))`
	String Comparison
`=` `==`	is equal toThe == comparison operator behaves differently within a double-brackets test than within single brackets. `[[ $a == z* ]] # True if $a starts with an "z" (pattern matching).` `[[ $a == "z" ]] # True if $a is equal to z (literal matching).` `[ $a == z* ] # File globbing and word splitting take place.` `[ "$a" == "z" ] # True if $a is equal to z (literal matching).`
`!=`	is not equal to`if [ "$a" != "$b" ]`This operator uses pattern matching within a [[ ... ]] construct.
`<`	is less than, in ASCII alphabetical orderNote that the `<` needs to be escaped within a [ ] construct.`if [[ "$a" < "$b" ]] if [ "$a" \< "$b" ]`
`>`	is greater than, in ASCII alphabetical order.Note that the `>` needs to be escaped within a [ ] construct.`if [[ "$a" > "$b" ]] if [ "$a" \> "$b" ]`
`-z`	string is null that is, has zero length `if [ -z "$s" ]`
`-n`	string is not null.`if [ -n "$s" ]`
	File Test Operators
`-e` `-a`	file exists`-a` is deprecated and its use is discouraged.
`-f`	file is a regular file (not a directory or device file)
`-d`	file is a directory
`-h` `-L`	file is a symbolic link
`-b`	file is a block device
`-c`	file is a character device
`-p`	file is a pipe
`-S`	file is a socket
`-s`	file is not zero size
`-t`	file (descriptor) is associated with a terminal device This test option may be used to check whether the `stdin [ -t 0 ]` or `stdout [ -t 1 ]` in a given script is a terminal.
`-r`	file has read permission (for the user running the test)
`-w`	file has write permission (for the user running the test)
`-x`	file has execute permission (for the user running the test)
`-g`	set-group-id (sgid) flag set on file or directory
`-u`	set-user-id (suid) flag set on file
`-k`	sticky bit set
`-O`	you are owner of file
`-G`	group-id of file same as yours
`-N`	file modified since it was last read
`-nt`	file f1 is newer than f2`if [ "$f1" -nt "$f2" ]`
`-ot`	file f1 is older than f2`if [ "$f1" -ot "$f2" ]`
`-ef`	files f1 and f2 are hard links to the same file`if [ "$f1" -ef "$f2" ]`
`!`	"not" -- reverses the sense of the tests above (returns true if condition absent).
	Compound Comparison
`-a`	logical `and`Similar to `&&`
`-o`	logical `or`Similar to `