How to use case statement on shell script linux

Question

im trying to create a script that check if user already registered before than add number after username for example username1 and will keep looping after i got unique username.

here what i try

username="tes2"
password="tes2"
exists=$(grep -c "^$username:" /etc/passwd)
case=$exists
i=1

while true
do
    case "$case" in
        *)
            echo 'generate new user'
            i=$(( $i + 1 ))
            username="$username""$i"
            exists=$(grep -c "^$username:" /etc/passwd)
            case=$exists;;
        0) 
            pass=$(perl -e 'print crypt($ARGV[0], "password")' $password)
            useradd -m -p "$pass" "$username"
            echo 'success add $username' 
            break;;
    esac
done

echo "Quit"

when i run this script, it keep generate new user.

Try shellcheck, it automatically finds problems in scripts like "Line 10: This pattern always overrides a later one on line 16." — that other guy
– that other guy, Commented Jun 24, 2020 at 18:10

Nate Eldredge · Accepted Answer · 2020-06-24 18:10:20Z

5

https://tldp.org/LDP/Bash-Beginners-Guide/html/sect_07_03.html

The commands in the COMMAND-LIST for the first match are executed.

https://www.gnu.org/software/bash/manual/bash.html#Conditional-Constructs

case will selectively execute the command-list corresponding to the first pattern that matches word.

* always matches so it's always executed. If you want the 0 case to execute when it matches, put it before the * case.

edited Jun 24, 2020 at 18:10

answered Jun 24, 2020 at 18:08

Nate Eldredge

62.4k7 gold badges78 silver badges121 bronze badges

Sign up to request clarification or add additional context in comments.

1 Comment

chepner Over a year ago

gnu.org/software/bash/manual/bash.html#Conditional-Constructs would be a much better source to cite.

dbc · Accepted Answer · 2024-06-16 14:51:49Z

0

#!/bin/bash


check_passwd() {
    if [ ! -f ./passwd_copy.txt ]; then
    echo "brak pliku passwd_copy.txt, aby utworzyc uruchom skrypt z poleceniem -INIT";
    exit 1
    fi
}

case $1 in
    "-AUTHOR")
        echo "Autor skryptu: $autor";
        echo "Grupa szkoleniowa $grupa";
        echo "Nazwa skryptu: $0";
    ;;
    "-INIT")
        if [ $(cp /etc/passwd ./passwd_copy.txt) ] ; then
        echo "kopia nie ok";
        else
        echo "kopia ok";
        fi
    ;;
    "-FIND")
        check_passwd
        if [ -z "$2" ]; then
        echo "brak ciagu do wyszukania"
        exit 1
        fi
        grep "$2" passwd_copy.txt > wynik_$(date +%d-%m-%Y).txt 
    ;;
    "-COLUMNS")
        check_passwd
        if [ -z "$2" ]; then
        echo "Brak numeru kolumny"
        exit 1
        fi
        awk -v col="$2" -F: '{print $col}' passwd_copy.txt 1>$2
    ;;
    "-RIGHTS")
        check_passwd
        if [ -z "$2" ] || [ -z "$3" ]; then
        echo "brak katalogu lub praw"
        exit 1
        fi
        for file in "$2"/*; do
        if [ -f "$file" ]; then
        chmod "$3" "$file"
        echo "zmieniono prawa dla pliku $file"
        fi
        done
    ;;
    *)
        echo "MoÅ¼liwe do wpisania parametry to -AUTHOR -INIT -FIND -COLUMNS -RIGHTS";
    esac

edited Jun 16, 2024 at 14:51

dbc

120k27 gold badges273 silver badges404 bronze badges

answered Jun 16, 2024 at 7:30

Steve Col

1

1 Comment

dbc Over a year ago

Thank you for posting this answer. While this code may answer the question, might you please edit your post to add an explanation as to why/how it works? This can help future readers learn and apply your answer. You are also more likely to get positive feedback (upvotes) when you include an explanation.

Collectives™ on Stack Overflow

How to use case statement on shell script linux

2 Answers 2

1 Comment

1 Comment

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

2 Answers 2

1 Comment

1 Comment

Your Answer

Sign up or log in

Post as a guest

Related