Test evaluates the expression expr. If the value is true the exit
status is null; otherwise the exit status is non–null. If there
are no arguments the exit status is non–null. |
The following primitives are used to construct expr.
–r file True if the file exists (is accessible) and is readable.
–w file True if the file exists and is writable.
–x file True if the file exists and has execute permission.
–e file True if the file exists.
–f file True if the file exists and is a plain file.
–d file True if the file exists and is a directory.
–s file True if the file exists and has a size greater than zero.
–t fildes True if the open file whose file descriptor number is
fildes (1 by default) is the same file as /dev/cons.
–A file True if the file exists and is append–only.
–L file True if the file exists and is exclusive–use.
–Tfile True if the file exists and is temporary.
s1 = s2 True if the strings s1 and s2 are identical.
s1 != s2 True if the strings s1 and s2 are not identical.
s1 True if s1 is not the null string. (Deprecated.)
–n s1 True if the length of string s1 is non–zero.
–z s1 True if the length of string s1 is zero.
n1 –eq n2True if the integers n1 and n2 are arithmetically equal.
Any of the comparisons –ne, –gt, –ge, –lt, or –le may be used in place
a –nt b True if file a is newer than (modified after) file b.
a –ot b True if file a is older than (modified before) file b.
f –older tTrue if file f is older than (modified before) time t.
If t is a integer followed by the letters y(years), M(months),
d(days), h(hours), m(minutes), or s(seconds), it represents current
time minus the specified time. If there is no letter, it represents
seconds since epoch. You can also concatenate mixed units.
These primaries may be combined with the following operators:
For example, 3d12h means three days and twelve hours ago. |
! unary negation operator
–o binary or operator
–a binary and operator; higher precedence than –o
( expr ) parentheses for grouping.
The primitives –b, –u, –g, and –s return false; they are recognized
for compatibility with POSIX.
Notice that all the operators and flags are separate arguments
to test. Notice also that parentheses and equal signs are meaningful
to rc and must be enclosed in quotes.