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 ,