Page MenuHomeFreeBSD
Files F144689589

D48154.diff
No OneTemporary
Actions

D48154.diff
View Options

diff --git a/sbin/devd/devd.conf.5 b/sbin/devd/devd.conf.5
--- a/sbin/devd/devd.conf.5
+++ b/sbin/devd/devd.conf.5
@@ -38,7 +38,7 @@
.\" ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS
.\" SOFTWARE.
.\"
-.Dd March 6, 2024
+.Dd December 20, 2024
.Dt DEVD.CONF 5
.Os
.Sh NAME
@@ -694,6 +694,26 @@
// part of the previous comment.
.Ed
.Ss Notes on Variable Expansion
+Variables are expanded by preceding them by a
+.Dq $
+sign.
+Any text immediately following that sign, starting with a letter, a minus sign
+.Dq - ,
+an underscore
+.Dq _ ,
+or an asterisk
+.Dq *
+is considered an internal variable, and expanded accordingly.
+If that variable does not exist, it silently expands to an empty string.
+Consequently, if the intention is to pass a
+.Xr sh 1
+variable, it must be surrounded by braces to prevent it from being
+considered an internal variable.
+.Pp
+See
+.Sx EXAMPLES
+for a detailed example.
+.Pp
To prevent issues with special shell characters, the following happens for each
variable
.Ic $foo .
@@ -711,6 +731,10 @@
.Ic foo
variable is inserted into the buffer with all single quote characters
prefixed by a backslash.
+.It
+A final
+.Dq '
+is inserted.
.El
.Pp
See
@@ -822,6 +846,37 @@
};
.Ed
.Pp
+The following example illustrates the difference betwen internal and shell variables:
+.Bd -literal
+attach 20 {
+ device-name "umodem[0-9]+";
+ match "vendor" "0x2047";
+ match "product" "0x001(0|3|4)";
+ match "interface" "0";
+ action "cd /dev; p=$product; dn=$device-name; \\
+ un=$(sysctl -n dev.umodem.${dn#umodem}.ttyname); \\
+ chmod 666 cua${un}; ln -sf cua${un} mspfet${p#0x}";
+};
+.Ed
+.Pp
+.Dq product ,
+and
+.Dq device-name
+are internal variables.
+Their contents are initially assigned to shell variables
+.Dq p ,
+and
+.Dq dn ,
+respectively.
+Then, variable
+.Dq dn
+is used inside a shell command substitution, assigning to shell variable
+.Dq un .
+Finally, this shell variable is used in two other shell statements, where
+it needs to be wrapped in braces in order to prevent it from being
+considered in internal variable to
+.Nm devd .
+.Pp
The installed
.Pa /etc/devd.conf
has many additional examples.

File Metadata

Mime Type
text/plain
Expires
Thu, Feb 12, 4:31 AM (5 h, 21 m)
Storage Engine
blob
Storage Format
Raw Data
Storage Handle
28663862
Default Alt Text
D48154.diff (2 KB)

Event Timeline