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-rw-r--r--bin/expr/expr.131
1 files changed, 21 insertions, 10 deletions
diff --git a/bin/expr/expr.1 b/bin/expr/expr.1
index 3f8eabbdde66..5c3cb4471e40 100644
--- a/bin/expr/expr.1
+++ b/bin/expr/expr.1
@@ -30,7 +30,7 @@
.\"
.\" $FreeBSD$
.\"
-.Dd July 12, 2004
+.Dd September 9, 2010
.Dt EXPR 1
.Os
.Sh NAME
@@ -217,6 +217,9 @@ command, one might rearrange the expression:
More generally, parenthesize possibly-negative values:
.Dl "a=$(expr \e( $a \e) + 1)"
.It
+With shell arithmetic, no escaping is required:
+.Dl "a=$((a + 1))"
+.It
This example prints the filename portion of a pathname stored
in variable
.Va a .
@@ -229,6 +232,12 @@ The
.Li //
characters resolve this ambiguity.
.Dl "expr \*q//$a\*q \&: '.*/\e(.*\e)'"
+.It
+With modern
+.Xr sh 1
+syntax,
+.Dl "\*q${a##*/}\*q"
+expands to the same value.
.El
.Pp
The following examples output the number of characters in variable
@@ -237,19 +246,21 @@ Again, if
.Va a
might begin with a hyphen, it is necessary to prevent it from being
interpreted as an option to
-.Nm .
+.Nm ,
+and
+.Va a
+might be interpreted as an operator.
.Bl -bullet
.It
-If the
-.Nm
-command conforms to
-.St -p1003.1-2001 ,
-this is simple:
-.Dl "expr -- \*q$a\*q \&: \*q.*\*q"
-.It
-For portability to older systems, however, a more complicated command
+To deal with all of this, a complicated command
is required:
.Dl "expr \e( \*qX$a\*q \&: \*q.*\*q \e) - 1"
+.It
+With modern
+.Xr sh 1
+syntax, this can be done much more easily:
+.Dl "${#a}"
+expands to the required number.
.El
.Sh SEE ALSO
.Xr sh 1 ,