【Linux/Unix】csh中循环方法

微思研 2022-09-27

4168

1 简介

C shell(csh)以及升级版(tcsh)都是Unix shell，最初于20世纪70年代末期被加州大学伯克利分校的Bill Joy创建的。

2 语法

while ( condition )
  # do something
  # command 1
  # command 2
end

或者

set i = 1
while ( i < 5 ) 
    # do something till i < 5 
    # command 1 
    # command 2 
    @ i++   # 注意这里的 @ 
end

或者

foreach n ( 1 2 3 4 5 )
  #command1
  #command2
end

3 示例

3.1 示例1

# 代码
 #!/bin/csh
 # demoloop.csh - Sample loop script
 set j = 1
 while ( $j <= 5 )
   echo "Welcome $j times"
   @ j++
 end


# 运行
chmod +x demoloop.csh
./demoloop.csh


# 结果
Welcome 1 times
Welcome 2 times
Welcome 3 times
Welcome 4 times
Welcome 5 times

3.2 示例2

#代码
#!/bin/csh
echo "Setting name servers...."
foreach i ( ns1.cyberciti.biz ns2.cyberciti.biz  ) 
   echo $i 
end


# 运行结果
Setting name servers....
ns1.cyberciti.biz
ns2.cyberciti.biz

3.3 示例3

#!/bin/csh
foreach i (*)
        if (-f $i) then
            echo "$i is a file."
        endif
        if (-d $i) then
             echo "$i is a directory."
        endif
end


# 输出结果
mycal.pl is a file.
skl is a directory.
x is a file.
x.pl is a file.
y is a file.

4 说明

除非是使用的内容是使用csh编写的，否则推荐使用shell(sh)。说明原文如下：
Please note that csh was popular for many innovative features but csh has never been as popular for scripting. If you are writing system level rc scripts avoid using csh. You may want to use bin/sh for any scripts that might have to run on other systems.

本人CSDN博客主页：

https://blog.csdn.net/weixin_44237659?spm=1011.2124.3001.5343

unix linux系统

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