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true(1) [bsd man page]

TRUE(1) 						      General Commands Manual							   TRUE(1)

NAME
true, false - provide truth values SYNOPSIS
true false DESCRIPTION
True and false are usually used in a Bourne shell script. They test for the appropriate status "true" or "false" before running (or fail- ing to run) a list of commands. EXAMPLE
while true do command list done SEE ALSO
csh(1), sh(1), false(1) DIAGNOSTICS
True has exit status zero. 7th Edition April 29, 1985 TRUE(1)

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TEST(1) 						      General Commands Manual							   TEST(1)

NAME
test - condition evaluation utility SYNOPSIS
test expression DESCRIPTION
The test utility evaluates the expression and, if it evaluates to true, returns a zero (true) exit status; otherwise it returns 1 (false). If there is no expression, test also returns 1 (false). All operators and flags are separate arguments to the test utility. The following primaries are used to construct expression: -b file True if file exists and is a block special file. -c file True if file exists and is a character special file. -d file True if file exists and is a directory. -e file True if file exists (regardless of type). -f file True if file exists and is a regular file. -g file True if file exists and its set group ID flag is set. -h file True if file exists and is a symbolic link. -n string True if the length of string is nonzero. -p file True if file is a named pipe -r file True if file exists and is readable. -s file True if file exists and has a size greater than zero. -t [file_descriptor] True if the file whose file descriptor number is file_descriptor (default 1) is open and is associated with a terminal. -u file True if file exists and its set user ID flag is set. -w file True if file exists and is writable. True indicates only that the write flag is on. The file is not writable on a read-only file system even if this test indicates true. -x file True if file exists and is executable. True indicates only that the execute flag is on. If file is a directory, true indicates that file can be searched. -z string True if the length of string is zero. string True if string is not the null string. s1 = s2 True if the strings s1 and s2 are identical. s1 != s2 True if the strings s1 and s2 are not identical. n1 -eq n2 True if the integers n1 and n2 are algebraically equal. n1 -ne n2 True if the integers n1 and n2 are not algebraically equal. n1 -gt n2 True if the integer n1 is algebraically greater than the integer n2 . n1 -ge n2 True if the integer n1 is algebraically greater than or equal to the integer n2 . n1 -lt n2 True if the integer n1 is algebraically less than the integer n2 . n1 -le n2 True if the integer n1 is algebraically less than or equal to the integer n2 . These primaries can be combined with the following operators: ! expression True if expression is false. expression1 -a expression2 True if both expression1 and expression2 are true. expression1 -o expression2 True if either expression1 or expression2 are true. (expression) True if expression is true. The -a operator has higher precedence than the -o operator. GRAMMAR AMBIGUITY
The test grammar is inherently ambiguous. In order to assure a degree of consistency, the cases described in the IEEE Std 1003.2 ("POSIX"), section D11.2/4.62.4, standard are evaluated consistently according to the rules specified in the standards document. All other cases are subject to the ambiguity in the command semantics. RETURN VALUES
The test utility exits with one of the following values: 0 expression evaluated to true. 1 expression evaluated to false or expression was missing. >1 An error occurred. BUGS
Named pipes are not implemented in 2.11BSD. STANDARDS
The test function is expected to be IEEE Std 1003.2 ("POSIX") compatible. 7th Edition March 13, 1995 TEST(1)

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