如何在‘`su << <<EOF`’内‘`cat $user’EOF‘？

Question

##!/bin/bash
set -e
backup_dir='/home/my/backup'
user='my'

su $user <<EOFHD
cat << 'EOF' > $backup_dir/autorestartnftables.sh
#!/bin/bash
SERVICENAME="nftables"

# return value is 0 if running
STATUS=$?
if [[ "$STATUS" -ne "0" ]]; then
        echo "Service '$SERVICENAME' is not curently running... Starting now..."
        systemctl start $SERVICENAME
fi
EOF
chmod +x $backup_dir/autorestartnftables.sh
EOFHD

上面的脚本用于创建autorestartnftables.sh，预期结果如下：

#!/bin/bash
SERVICENAME="nftables"
# return value is 0 if running
STATUS=$？
if [[ "$STATUS" -ne "0" ]]; then
        echo "Service '$SERVICENAME' is not curently running... Starting now..."
        systemctl start $SERVICENAME
fi

运行后的autorestartnftables.sh sudo bash ./example.sh

#!/bin/bash
SERVICENAME="nftables"
# return value is 0 if running
STATUS=0
if [[ "" -ne "0" ]]; then
        echo "Service '' is not curently running... Starting now..."
        systemctl start 
fi

问题出在哪里？

Answer 1

不要筑巢，巢，巢。相反，使用declare -f和函数将工作转移到不相关的上下文。

##!/bin/bash
set -e
backup_dir='/home/my/backup'
user='my'
work() {
    cat << 'EOF' > $backup_dir/autorestartnftables.sh
#!/bin/bash
SERVICENAME="nftables"

# return value is 0 if running
STATUS=$?
if [[ "$STATUS" -ne "0" ]]; then
        echo "Service '$SERVICENAME' is not curently running... Starting now..."
        systemctl start $SERVICENAME
fi
EOF
    chmod +x $backup_dir/autorestartnftables.sh
}
su "$user" bash -c "$(declare -p backup_dir); $(declare -f work); work"

在这种情况下，您可以检查运行脚本的用户是否是您想要的用户，然后使用该用户重新启动脚本：

##!/bin/bash
set -e
backup_dir='/home/my/backup'
user='my'
if [[ "$USER" != "$user" ]]; then
   # restart yourself as that user
   exec sudo -u "$user" "$0" "$@"
fi

cat << 'EOF' > $backup_dir/autorestartnftables.sh
#!/bin/bash
SERVICENAME="nftables"

# return value is 0 if running
STATUS=$?
if [[ "$STATUS" -ne "0" ]]; then
        echo "Service '$SERVICENAME' is not curently running... Starting now..."
        systemctl start $SERVICENAME
fi
EOF
chmod +x $backup_dir/autorestartnftables.sh

用外壳检查检查您的脚本。