Shulou(Shulou.com)06/03 Report--

In this issue, the editor will bring you about how to use shell scripts to verify the validity of user input parameters. The article is rich in content and analyzes and describes for you from a professional point of view. I hope you can get something after reading this article.

Today's example is used to verify the validity of the parameters entered by the user. The program is not complicated, as shown below:

#! / bin/sh# validAlphaNum-Ensures that input consists only of alphabetical# and numeric characters.validAlphaNum () {# Validate arg: returns 0 if all upper+lower+digits, 1 otherwise # Remove all unacceptable chars compressed= "$(echo $1 | sed-e's / [^ [: alnum:]] / / g')" if ["$compressed"! = "$input"]; then return 1 else return 0 fi} # Sample usage of this function in a scriptecho-n "Enter input:" read inputif! ValidAlphaNum "$input"; then # / / this is a bit clever, that is, if the return value of the function is 1, execute echo "Your input must consist of only letters and numbers." > & 2 exit 1else echo "Input is valid." fiexit 0

As mentioned above, the script flow and ideas are very simple, that is, your input is filtered by sed and compared with the original input, and if it is not equal, the input is illegal.

It is worth noting that there are

1) sed-e's / [^ [: alnum:]] / / g'([: alnum:] means uppercase and lowercase letters and numbers, where the function of sed is to filter out non-uppercase and lowercase letters and numbers.

2) if! ValidAlphaNum "$input" $input is called as an argument to the function, notice that it is in quotation marks.

The above is how to use the shell script to verify the validity of the parameters entered by the user. If you happen to have similar doubts, you might as well refer to the above analysis to understand. If you want to know more about it, you are welcome to follow the industry information channel.

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