set file = "example.txt" if (-e $file) then echo "The file exists." else echo "The file does not exist." endif 在这个例子中,我们通过if语句判断文件"example.txt"是否存在。如果条件成立,即文件存在,那么输出"The file exists.";否则,输出"The file does not exist."。 例子3:判断一个字符串...
13) if/else/switch/case if(expression)then commands endif if {(command)} then commands endif if(expression) then commands else if(expression) then commands else commands endif switch("$value") case pattern1: commands breaksw case pattern2: commands breaksw default: commands breaksw endsw 14 ...
-w file file is writable by user -x file file is executable by user -o file file is owned by user -z file file has size 0 -f file file is an ordinary file -d file file is a directory ! -- negate && -- logical and || -- logical or #if-else # run cmd as if expression ...
% echo "test set noclobber" > testfile testfile: File exists. % echo "test set noclobber" >! testfile % 例子二: 代码如下: % set noclobber % cat /etc/passwd >> nopass nopass: No such file or directory % cat /etc/passwd >>! nopass %...
if {(command)} then commands endif if(expression) then commands else if(expression) then commands else commands endif switch("$value") case pattern1: commands breaksw case pattern2: commands breaksw default: commands breaksw endsw 1.
-x file file is executable by user -o file file is owned by user -z file file has size 0 -f file file is an ordinary file -d file file is a directory ! -- negate && -- logical and || -- logical or #if-else # run cmd as if expression ...
else if(expression) then commands else commands endif switch("$value") case pattern1: commands breaksw case pattern2: commands breaksw default: commands breaksw endsw 14 while/foreach 复制代码代码如下: while(expression) commands continue
Return true, or 1 if the user has read access. Otherwise it returns false, or 0. -w filename True if the user has write access. -x filename True if the user has execute permission (or search permission on a directory). -e filename True if filename exists. -o filename True...
用来检查用户是否对某个节点进行过投票。...downvoted_by(self, user): return self.down_votes.filter(user=user).exists()然后,在视图中,我们可以使用这些方法来检查用户是否对某个帖子进行过投票...down="{%if node.pk in downvoted_comments %}{% endif %}" ...通过上述方法,可以高效地检查...
Csh的基本语法介绍 在*unix系统中，常⽤的shell有sh，bash，csh/tcsh, ksh.sh来⾃于systemV的Unix，是传统的Unix的shell，直到现在很多的系统管理员仍然喜欢使⽤sh。bash来⾃于BSD Unix，语法⾮常类似于C语⾔，所以通常有C/C++编程背景的开发⼈员最喜欢使⽤。ksh是对sh的扩展，且吸收了csh的⼀...