Added expr, from Edward Betts <edward@debian.org>, with some fixups

and docs added by me.
 -Erik

1 files changed, 40 insertions, 1 deletions

diff --git a/docs/busybox.pod b/docs/busybox.pod
index accdaed23..3bedcefb7 100644
--- a/docs/busybox.pod
+++ b/docs/busybox.pod
@@ -497,6 +497,45 @@ Example:
 
 -------------------------------
 
+=item echo
+
+
+Usage: expr EXPRESSION
+
+Prints the value of EXPRESSION to standard output.
+
+EXPRESSION may be:
+
+        ARG1 |  ARG2    ARG1 if it is neither null nor 0, otherwise ARG2
+        ARG1 &  ARG2    ARG1 if neither argument is null or 0, otherwise 0
+        ARG1 <  ARG2    ARG1 is less than ARG2
+        ARG1 <= ARG2    ARG1 is less than or equal to ARG2
+        ARG1 =  ARG2    ARG1 is equal to ARG2
+        ARG1 != ARG2    ARG1 is unequal to ARG2
+        ARG1 >= ARG2    ARG1 is greater than or equal to ARG2
+        ARG1 >  ARG2    ARG1 is greater than ARG2
+        ARG1 +  ARG2    arithmetic sum of ARG1 and ARG2
+        ARG1 -  ARG2    arithmetic difference of ARG1 and ARG2
+        ARG1 *  ARG2    arithmetic product of ARG1 and ARG2
+        ARG1 /  ARG2    arithmetic quotient of ARG1 divided by ARG2
+        ARG1 %  ARG2    arithmetic remainder of ARG1 divided by ARG2
+        STRING : REGEXP             anchored pattern match of REGEXP in STRING
+        match STRING REGEXP         same as STRING : REGEXP
+        substr STRING POS LENGTH    substring of STRING, POS counted from 1
+        index STRING CHARS          index in STRING where any CHARS is found, or 0
+        length STRING               length of STRING
+        quote TOKEN                 interpret TOKEN as a string, even if it is a
+                                                                        keyword like `match' or an operator like `/'
+        ( EXPRESSION )              value of EXPRESSION
+
+Beware that many operators need to be escaped or quoted for shells.
+Comparisons are arithmetic if both ARGs are numbers, else
+lexicographical.  Pattern matches return the string matched between
+\( and \) or null; if \( and \) are not used, they return the number
+of characters matched or 0.
+
+-------------------------------
+
 =item false
 
 Returns an exit code of FALSE (1)
@@ -2112,4 +2151,4 @@ Enrique Zanardi <ezanardi@ull.es>
 
 =cut
 
-# $Id: busybox.pod,v 1.65 2000/09/01 16:12:57 andersen Exp $
+# $Id: busybox.pod,v 1.66 2000/09/05 17:37:48 andersen Exp $