mirror of
https://codeberg.org/libreboot/lbmk.git
synced 2026-03-25 21:39:03 +02:00
e9a910b33c
i currently use the output of sha512sum in several places of xbmk, which is a bit unreliable in case output changes. other cases where i use util outputs in variables are probably reliable, because i'm using mostly posix utilities in those. to mitigate this, i now import suckless sbase, which has a reasonable sha512sum implementation. *every* binary it builds is being placed in build.list, because i'll probably start using more of them. for example, i may start modifying the "date" implementation, adding the GNU-specific options that i need as mentioned on init.sh i'm importing it in util/ because the sha512sum util is needed for verifying project sources, so if sbase itself is a "project source", that means we can into a chicken and egg bootstrapping problem. this is sbase at revision: 055cc1ae1b3a13c3d8f25af0a4a3316590efcd48 Signed-off-by: Leah Rowe <leah@libreboot.org>
102 lines
1.7 KiB
Groff
102 lines
1.7 KiB
Groff
.Dd October 8, 2015
|
|
.Dt EXPR 1
|
|
.Os sbase
|
|
.Sh NAME
|
|
.Nm expr
|
|
.Nd evaluate expression
|
|
.Sh SYNOPSIS
|
|
.Nm
|
|
.Ar expression
|
|
.Sh DESCRIPTION
|
|
.Nm
|
|
evaluates
|
|
.Ar expression
|
|
and writes the result to stdout.
|
|
.Pp
|
|
There are two elemental expressions,
|
|
.Sy integer
|
|
and
|
|
.Sy string .
|
|
Let
|
|
.Sy expr
|
|
be a non-elemental expression and
|
|
.Sy expr1 ,
|
|
.Sy expr2
|
|
arbitrary expressions.
|
|
Then
|
|
.Sy expr
|
|
has the recursive form
|
|
.Sy expr = [(] expr1 operand expr2 [)] .
|
|
.Pp
|
|
With
|
|
.Sy operand
|
|
being in order of increasing precedence:
|
|
.Bl -tag -width Ds
|
|
.It |
|
|
Evaluate to
|
|
.Sy expr1
|
|
if it is neither an empty string nor 0; otherwise evaluate to
|
|
.Sy expr2 .
|
|
.It &
|
|
Evaluate to
|
|
.Sy expr1
|
|
if
|
|
.Sy expr1
|
|
and
|
|
.Sy expr2
|
|
are neither empty strings nor 0; otherwise evaluate to 0.
|
|
.It = > >= < <= !=
|
|
If
|
|
.Sy expr1
|
|
and
|
|
.Sy expr2
|
|
are integers, evaluate to 1 if the relation is true and 0 if it is false.
|
|
If
|
|
.Sy expr1
|
|
and
|
|
.Sy expr2
|
|
are strings, apply the relation to the return value of
|
|
.Xr strcmp 3 .
|
|
.It + -
|
|
If
|
|
.Sy expr1
|
|
and
|
|
.Sy expr2
|
|
are integers, evaluate to their sum or subtraction.
|
|
.It * / %
|
|
If
|
|
.Sy expr1
|
|
and
|
|
.Sy expr2
|
|
are integers, evaluate to their multiplication, division or remainder.
|
|
.It :
|
|
Evaluate to the number of characters matched in
|
|
.Sy expr1
|
|
against
|
|
.Sy expr2 . expr2
|
|
is anchored with an implicit '^'.
|
|
.Pp
|
|
You can't directly match the empty string, since zero matched characters
|
|
resolve equally to a failed match.
|
|
To work around this limitation, use "expr X'' : 'X$' instead of "expr ''
|
|
: '$'"
|
|
.El
|
|
.Sh EXIT STATUS
|
|
.Bl -tag -width Ds
|
|
.It 0
|
|
.Ar expression
|
|
is neither an empty string nor 0.
|
|
.It 1
|
|
.Ar expression
|
|
is an empty string or 0.
|
|
.It 2
|
|
.Ar expression
|
|
is invalid.
|
|
.It > 2
|
|
An error occurred.
|
|
.El
|
|
.Sh SEE ALSO
|
|
.Xr test 1
|
|
.Sh STANDARDS
|
|
POSIX.1-2013.
|