معمل 19.1: Write admin scripts

هذا الجزء لم يُترجم بعد. أنت ترى النص الإنجليزي.

الهدف

Write three small scripts that use arguments, tests, loops and case — the kind of task the exam and daily work ask for.

قبل أن تبدأ

Work on server1 as root. Put the scripts in /usr/local/bin/.

المهام

Script mkusers.sh: reads a file given as the first argument, with one user name per line, and creates each user if it does not exist yet. Without an argument it prints a usage line and exits with code 1.
Script diskcheck.sh: prints "WARNING: / is NN% full" when the root file system is more than 80 % full, else "OK". It takes the limit as an optional argument (default 80).
Script web.sh: with the argument start, stop or status it does that with httpd; with anything else it prints a usage line and exits with 1.
Check the syntax of all three scripts and run one of them with tracing.

تحقّق من عملك

#printf 'tom\njerry\ntom\n' > /tmp/names.txt
#mkusers.sh /tmp/names.txt; id tom; id jerry
#mkusers.sh; echo $?
#diskcheck.sh; diskcheck.sh 1
#web.sh status; web.sh foo; echo $?

tom and jerry exist; the second "tom" gives no error.
Without arguments the scripts print a usage line and $? is 1.
diskcheck.sh 1 prints a WARNING.

تلميحات

اعرض التلميحات

[ $# -lt 1 ], while read -r NAME, id "$NAME" &>/dev/null.
df --output=pcent / | tail -1 | tr -dc '0-9' gives the number.
case "$1" in start|stop|status) … ;; *) … ;; esac.
bash -n FILE, bash -x FILE.

الحل

اعرض الحل

mkusers.sh

/usr/local/bin/mkusers.sh

#!/bin/bash
if [ $# -lt 1 ] || [ ! -f "$1" ]; then
    echo "usage: $0 FILE" >&2
    exit 1
fi
while read -r NAME; do
    [ -z "$NAME" ] && continue
    if id "$NAME" &>/dev/null; then
        echo "$NAME exists"
    else
        useradd "$NAME" && echo "$NAME created"
    fi
done < "$1"

diskcheck.sh

/usr/local/bin/diskcheck.sh

#!/bin/bash
LIMIT=${1:-80}
USED=$(df --output=pcent / | tail -1 | tr -dc '0-9')
if [ "$USED" -gt "$LIMIT" ]; then
    echo "WARNING: / is ${USED}% full"
else
    echo "OK"
fi

web.sh

/usr/local/bin/web.sh

#!/bin/bash
case "$1" in
    start|stop|status)
        systemctl "$1" httpd ;;
    *)
        echo "usage: $0 {start|stop|status}" >&2
        exit 1 ;;
esac

Make them executable, check and trace.

#chmod +x /usr/local/bin/{mkusers,diskcheck,web}.sh
#for f in /usr/local/bin/{mkusers,diskcheck,web}.sh; do bash -n "$f" && echo "$f OK"; done
#bash -x /usr/local/bin/diskcheck.sh 50

Write admin scripts

الهدف

قبل أن تبدأ

المهام

تحقّق من عملك

تلميحات

الحل

ملاحظاتي

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