.TH TEST 1
.SH NAME
test \- set status according to condition
.SH SYNOPSIS
.B test
.I expr
.SH DESCRIPTION
.I Test
evaluates the expression
.IR 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.
.PP
The following primitives are used to construct
.IR expr .
.TP "\w'\fIn1 \fL-eq \fIn2\fLXX'u"
.BI -r " file"
True if the file exists (is accessible) and is readable.
.PD0
.TP
.BI -w " file"
True if the file exists and is writable.
.TP
.BI -x " file"
True if the file exists and has execute permission.
.TP
.BI -e " file
True if the file exists.
.TP
.BI -f " file"
True if the file exists and is a plain file.
.TP
.BI -d " file"
True if the file exists and is a directory.
.TP
.BI -s " file"
True if the file exists and has a size greater than zero.
.TP
.BI -t " fildes
True if the open file whose file descriptor number is
.I fildes
(1 by default)
is the same file as
.BR /dev/cons .
.TP
.BI -A " file"
True if the file exists and is append-only.
.TP
.BI -L " file"
True if the file exists and is exclusive-use.
.TP
.BI -T " file"
True if the file exists and is temporary.
.TP
.IB s1 " = " s2
True
if the strings
.I s1
and
.I s2
are identical.
.TP
.IB s1 " != " s2
True
if the strings
.I s1
and
.I s2
are not identical.
.TP
s1
True if
.I s1
is not the null string.
(Deprecated.)
.TP
.BI -n " s1"
True if the length of string
.I s1
is non-zero.
.TP
.BI -z " s1"
True if the length of string
.I s1
is zero.
.TP
.IB n1 " -eq " n2
True if the integers
.I n1
and
.I n2
are arithmetically equal.
Any of the comparisons
.BR -ne ,
.BR -gt ,
.BR -ge ,
.BR -lt ,
or
.BR -le
may be used in place of
.BR -eq .
The (nonstandard) construct
.BI -l " string\f1,
meaning the length of
.IR string ,
may be used in place of an integer.
.TP
.IB a " -nt " b
True if file
.I a
is newer than (modified after) file
.IR b .
.TP
.IB a " -ot " b
True if file
.I a
is older than (modified before) file
.IR b .
.TP
.IB f " -older " t
True if file
.I f
is older than (modified before) time
.IR t .
If
.I t
is a integer followed by the letters
.BR y (years),
.BR M (months),
.BR d (days),
.BR h (hours),
.BR m (minutes),
or
.BR 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.  For example,
.B 3d12h
means three days and twelve hours ago.
.PD
.PP
These primaries may be combined with the
following operators:
.TP "\w'\fL( \fIexpr\fL )XX'u"
.B  !
unary negation operator
.PD0
.TP
.B  -o
binary
.I or
operator
.TP
.B  -a
binary
.I and
operator; higher precedence than
.BR -o
.TP
.BI "( " expr " )"
parentheses for grouping.
.PD
.PP
The primitives
.BR -b ,
.BR -u ,
.BR -g ,
and
.BR -s
return false; they are recognized for compatibility with POSIX.
.PP
Notice that all the operators and flags are separate
arguments to
.IR test .
Notice also that parentheses and equal signs are meaningful
to
.I rc
and must be enclosed in quotes.
.SH EXAMPLES
.I Test
is a dubious way to check for specific character strings:
it uses a process to do what an
.IR rc (1)
match or switch statement can do.
The first example is not only inefficient but wrong, because
.I test
understands the purported string
.B  \&"-c"
as an option.
.IP
.EX
if (test $1 '=' "-c") echo OK	# wrong!
.EE
.LP
A better way is
.IP
.EX
if (~ $1 -c) echo OK
.EE
.PP
Test whether 
.L abc
is in the current directory.
.IP
.B test -f abc -o -d abc
.SH SOURCE
.B /sys/src/cmd/test.c
.SH "SEE ALSO"
.IR rc (1) 
.SH BUGS
There is no way to test if a directory is writable, 
.B -w
always returns false for directories.