How to search user id and replace name in shell script Linux-CodePudding

For example A = UserID

user.txt content

A1:Alex:Password1
A2:John:Password2

Search A2 User ID and Replace John username as Alexander

echo -n "Enter user id: "
read userID

After i enter the user id, i need to search in user.txt, after found the user id Enter the replace name John.

Could people please help with how to do it. I tried a few executing instructions, but didn't work. How can i do it in Shell Script Linux ? Thanks

Thanks for helping I found the way how to do it from answer.

echo -n "Enter user id: "
read userID
echo -n "Enter user name: "
read userName

sed -i 's/'$userID':\w*/'$userID':'$userName'/g' user.txt

CodePudding user response：

Add to your bash script sed command as follow

#!/bin/bash
echo -n "Enter user id: "
read userID

sed -i 's/A2:\w*:/A2:'$userID':/g' user.txt

It will change in-place user.txt file

CodePudding user response：

Another simple method is using awk. You can pass the userID and replacement name from the shell to awk and then locate the record where the first field ($1) matches the userID and replace the name (3rd field $3) with the new one.

awk -v id="A2" -v nm="Alexander" -v OFS=":" -F: '$1==id {$3=nm}1' user.txt

The strings (or shell variables) are made awk variables through the -v=value parameters where id and nm are used to hold the userID and name as awk variables. -v OFS=":" sets the awk Output Field Separator to ":" so that after the records is modified with the new name, the ":" are replaced as separators. The -F: tells awk to use ":" as the Field Separator to separate the record (line) into fields. The 1 at the end is just shorthand for the default operation print to output the records.

Example Use/Output

Using a heredoc to supply your input you can do:

$ awk -v id="A2" -v nm="Alexander" -v OFS=":" -F: '$1==id {$3=nm}1' << eof
> A1:Alex:Password1
> A2:John:Password2
> eof
A1:Alex:Password1
A2:John:Alexander