utils-std

test.1 (8311B)

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.Dd October 5, 2016
.Dt TEST 1
.Os
.Sh NAME
.Nm test ,
.Nm \&[
.Nd condition evaluation utility
.Sh SYNOPSIS
.Nm
.Ar expression
.Nm \&[
.Ar expression Cm \&]
.Sh DESCRIPTION
The
.Nm
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,
.Nm
also
returns 1 (false).
.Pp
All operators and flags are separate arguments to the
.Nm
utility.
.Pp
When checking
.Ar file ,
one should consider TOCTOU race-conditions.
Avoiding the issue altogether with directly using
.Ar file
instead is strongly recommended.
.Pp
The following primaries are used to construct expression:
.Bl -tag -width Ar
.It Fl b Ar file
True if
.Ar file
exists and is a block special
file.
.It Fl c Ar file
True if
.Ar file
exists and is a character
special file.
.It Fl d Ar file
True if
.Ar file
exists and is a directory.
.It Fl e Ar file
True if
.Ar file
exists (regardless of type).
.It Ar file1 Fl ef Ar file2
True if
.Ar file1
and
.Ar file2
exist and refer to the same file.
.It Fl f Ar file
True if
.Ar file
exists and is a regular file.
.It Fl g Ar file
True if
.Ar file
exists and its set group ID flag
is set.
.It Fl h Ar file
True if
.Ar file
exists and is a symbolic link.
This operator is retained for compatibility with previous versions of
this program.
Do not rely on its existence; use
.Fl L
instead.
.It Fl L Ar file
True if
.Ar file
exists and is a symbolic link.
.It Fl k Ar file
True if
.Ar file
exists and its sticky bit is set.
.It Fl n Ar string
True if the length of
.Ar string
is nonzero.
.It Ar file1 Fl nt Ar file2
True if
.Ar file1
exists and is newer than
.Ar file2 .
.It Ar file1 Fl ot Ar file2
True if
.Ar file1
exists and is older than
.Ar file2 .
.It Fl p Ar file
True if
.Ar file
is a named pipe
.Pq Tn FIFO .
.It Fl r Ar file
True if
.Ar file
exists and is readable.
.It Fl S Ar file
True if
.Ar file
exists and is a socket.
.It Fl s Ar file
True if
.Ar file
exists and has a size greater
than zero.
.It Fl t Ar file_descriptor
True if the file whose file descriptor number
is
.Ar file_descriptor
is open and is associated with a terminal.
.It Fl u Ar file
True if
.Ar file
exists and its set user ID flag
is set.
.It Fl w Ar file
True if
.Ar 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.
.It Fl x Ar file
True if
.Ar file
exists and is executable.
True
indicates only that the execute flag is on.
If
.Ar file
is a directory, true indicates that
.Ar file
can be searched.
.It Fl z Ar string
True if the length of
.Ar string
is zero.
.It Fl O Ar file
True if
.Ar file
exists and its owner matches the effective user id of this process.
.It Fl G Ar file
True if
.Ar file
exists and its group matches the effective group id of this process.
.It Ar string
True if
.Ar string
is not the null
string.
.It Ar s1 Cm = Ar s2
True if the strings
.Ar s1
and
.Ar s2
are identical.
.It Ar s1 Cm != Ar s2
True if the strings
.Ar s1
and
.Ar s2
are not identical.
.It Ar s1 Cm < Ar s2
True if string
.Ar s1
comes before
.Ar s2
based on the binary value of their characters.
.It Ar s1 Cm > Ar s2
True if string
.Ar s1
comes after
.Ar s2
based on the binary value of their characters.
.It Ar n1 Fl eq Ar n2
True if the integers
.Ar n1
and
.Ar n2
are algebraically
equal.
.It Ar n1 Fl ne Ar n2
True if the integers
.Ar n1
and
.Ar n2
are not
algebraically equal.
.It Ar n1 Fl gt Ar n2
True if the integer
.Ar n1
is algebraically
greater than the integer
.Ar n2 .
.It Ar n1 Fl ge Ar n2
True if the integer
.Ar n1
is algebraically
greater than or equal to the integer
.Ar n2 .
.It Ar n1 Fl lt Ar n2
True if the integer
.Ar n1
is algebraically less
than the integer
.Ar n2 .
.It Ar n1 Fl le Ar n2
True if the integer
.Ar n1
is algebraically less
than or equal to the integer
.Ar n2 .
.El
.Pp
If
.Ar file
is a symbolic link,
.Nm
will fully dereference it and then evaluate the expression
against the file referenced, except for the
.Fl h
and
.Fl L
primaries.
.Pp
These primaries can be combined with the following operators:
.Bl -tag -width Ar
.It Cm \&! Ar expression
True if
.Ar expression
is false.
.It Ar expression1 Fl a Ar expression2
True if both
.Ar expression1
and
.Ar expression2
are true.
.It Ar expression1 Fl o Ar expression2
True if either
.Ar expression1
or
.Ar expression2
are true.
.It Cm \&( Ar expression Cm \&)
True if expression is true.
.El
.Pp
The
.Fl a
operator has higher precedence than the
.Fl o
operator.
.Pp
Some shells may provide a builtin
.Nm
command which is similar or identical to this utility.
Consult the
.Xr builtin 1
manual page.
.Sh GRAMMAR AMBIGUITY
The
.Nm
grammar is inherently ambiguous.
In order to assure a degree of consistency,
the cases described in the
.St -p1003.2 ,
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.
.Pp
In particular, only expressions containing
.Fl a ,
.Fl o ,
.Cm \&(
or
.Cm \&)
can be ambiguous.
.Sh EXIT STATUS
The
.Nm
utility exits with one of the following values:
.Bl -tag -width indent
.It 0
expression evaluated to true.
.It 1
expression evaluated to false or expression was
missing.
.It >1
An error occurred.
.El
.Sh EXAMPLES
Implement
.Li test FILE1 -nt FILE2
using only
.Tn POSIX
functionality:
.Pp
.Dl test -n \&"$(find -L -- FILE1 -prune -newer FILE2 2>/dev/null)\&"
.Pp
This can be modified using non-standard
.Xr find 1
primaries like
.Cm -newerca
to compare other timestamps.
.Sh COMPATIBILITY
For compatibility with some other implementations,
the
.Cm =
primary can be substituted with
.Cm ==
with the same meaning.
.Sh SEE ALSO
.Xr builtin 1 ,
.Xr expr 1 ,
.Xr find 1 ,
.Xr sh 1 ,
.Xr stat 1 ,
.Xr symlink 7
.Sh STANDARDS
.Nm
should be compliant with the
IEEE Std 1003.1-2024 (“POSIX.1”)
specification.
.Pp
The primaries
.Cm == ,
.Fl G ,
and
.Fl O
are extensions.
The
.Fl a ,
.Fl o
binary primaries, and
.Ql \&(
and
.Ql \&)
operators are kept for backward compatibility but should be taken as deprecated.
.Sh HISTORY
A
.Nm
utility appeared in
.At v7 .
.Sh BUGS
Both sides are always evaluated in
.Fl a
and
.Fl o .
For instance, the writable status of
.Pa file
will be tested by the following command even though the former expression
indicated false, which results in a gratuitous access to the file system:
.Dl "[ -z abc -a -w file ]"
To avoid this, write
.Dl "[ -z abc ] && [ -w file ]"