Bash Programming Cheat Sheet (Page 2 of 4) in pdf

Bash Programming Cheat Sheet Page 2

Bash Programming Cheat Sheet

Page 2 of 4

Logic and comparisons

A command called test is used to evaluate conditional expressions, such as a if-then statement that checks the

entrance/exit criteria for a loop.

test expression

[ expression ]

Numeric Comparisons

int1 -eq int2 Returns True if int1 is equal to int2.

int1 -ge int2 Returns True if int1 is greater than or equal to int2.

int1 -gt int2 Returns True if int1 is greater than int2.

int1 -le int2 Returns True if int1 is less than or equal to int2

int1 -lt int2 Returns True if int1 is less than int2

int1 -ne int2 Returns True if int1 is not equal to int2

String Comparisons

str1 = str2 Returns True if str1 is identical to str2.

str1 != str2 Returns True if str1 is not identical to str2.

str

Returns True if str is not null.

-n str

Returns True if the length of str is greater than zero.

-z str

Returns True if the length of str is equal to zero. (zero is different than null)

File Comparisons

-d filename Returns True if file, filename is a directory.

-f filename Returns True if file, filename is an ordinary file.

-r filename Returns True if file, filename can be read by the process.

-s filename Returns True if file, filename has a nonzero length.

-w filename Returns True if file, filename can be written by the process.

-x filename Returns True if file, filename is executable.

Expression Comparisons

!expression

Returns true if expression is not true

expr1 -a expr2

Returns True if expr1 and expr2 are true. ( && , and )

expr1 -o expr2

Returns True if expr1 or expr2 is true. ( ||, or )

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Bash Programming Cheat Sheet Page 2