bash Bash中$#有什么用
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What is the use of $# in Bash
提问by Lawrence Loh
I am very new to Bash scripting, can someone explain to me how the $# and $? work in the following code?
我对 Bash 脚本很陌生，有人可以向我解释 $# 和 $ 的用法吗？在以下代码中工作？
#!/bin/bash
ARGS=3 # Script requires 3 arguments.
E_BADARGS=85 # Wrong number of arguments passed to script.
if [ $# -ne "$ARGS" ]
then
echo "Usage: `basename # Builtin variables:
# There are some useful builtin variables, like
echo "Last program's return value: $?"
echo "Script's PID: $$"
echo "Number of arguments passed to script: $#"
echo "All arguments passed to script: $@"
echo "The script's name: script.sh 1
"
echo "Script's arguments separated into different variables: ..."
` old-pattern new-pattern filename"
exit $E_BADARGS
fi
old_pattern=
new_pattern=
if [ -f "" ]
then
file_name=
else
echo "File \"\" does not exist."
exit $E_BADARGS
fi
exit $?
回答by Thomas Ayoub
回答by user000001
From https://www.gnu.org/software/bash/manual/html_node/Special-Parameters.html
来自https://www.gnu.org/software/bash/manual/html_node/Special-Parameters.html
$#Expands to the number of positional parameters in decimal.
$?Expands to the exit status of the most recently executed foreground pipeline.
$#扩展到十进制位置参数的数量。
$?扩展到最近执行的前台管道的退出状态。
回答by ClaudioM
$#shows the number of the script's arguments
$?shows the last script's return value
$#显示脚本参数的数量
$?显示最后一个脚本的返回值
about arguments: echo "ARG[$#]"before ifand then execute the script like
关于参数：echo "ARG[$#]"之前if然后执行脚本，如
#shell>ls
file1.txt g inpu nodes_list
#shell>echo $?
0
#shell>ls FileNameNotFound
ls: FileNameNotFound: No such file or directory
#shell> echo $?
1
the ouput will be
输出将是
##代码##and so on
等等
the ouput of $?could be also used on the command line:
的输出$?也可以在命令行上使用：
