使用 Tcl 在 if 语句中评估表达式为真 [英] evaluating an expression to true in a if statement with Tcl
问题描述
我正在努力弄清楚如何使用 Tcl 计算 If 语句中的表达式.这就是我所拥有的:
I'm having serious biggies trying to figure out how to evaluate an expression in a If statement using Tcl. This is what I have:
#!/bin/sh
#The next line executes wish - wherever it is \
exec wish "$0" "$@"
set apid "/var/run/apache2.pid"
set apsta [file exist $apid]
if { $apsta == 1 }
{
set result ":)"
}
else
{
set result ":("
}
label .status -text $result
pack .status
这是我从终端得到的:
# wan27
Error in startup script: wrong # args: no script following " $apsta == 1 " argument
while executing
"if { $apsta == 1 }"
(file "/usr/bin/wan27" line 9)
如果 Apache 正在运行,我只是想输出一个快乐的笑脸,如果 Apache 停止则输出一个悲伤的笑脸 - 基于文件/var/run/apache2.pid"是否存在的布尔条件......
I'm just trying to output a happy smiley if Apache is running, a sad one if Apache is stopped - based upon the boolean condition whether or not the file "/var/run/apache2.pid" exists ...
推荐答案
Tcl if
语句的语法是
The syntax of a Tcl if
statement is
if condition statement else statement
必须在一行上.大括号允许跨行延续,并且它们的位置是强制性的:
which must be on one line. Braces allow continuation across lines and their placement is mandatory:
if { $apsta == 1 } {
set result ":)"
} else {
set result ":("
}
正如你所写的,Tcl 看到了
As you have it written, Tcl sees
if { $apsta == 1 }
并在那里停止产生语法错误.
and stops there yielding a syntax error.
这篇关于使用 Tcl 在 if 语句中评估表达式为真的文章就介绍到这了,希望我们推荐的答案对大家有所帮助,也希望大家多多支持IT屋!