数据裘: LinuxNotes

dreamable/LinuxNotes
ID	标题	笔记	标签
12	如何自动重启nginx	服务器nginx偶尔会被杀死，可能是系统资源不够了。 `sudo systemctl edit nginx` then paste in: `[Service] Restart=always` check if it works `sudo systemctl status nginx sudo pkill -f nginx sudo systemctl status nginx`
11	Install MQTT on Ubuntu 22.04	Install `sudo apt-get install mosquitto mosquitto-clients sudo mosquitto_passwd -c /etc/mosquitto/passwd <mqtt_user> (set passwd here) sudo vi /etc/mosquitto/conf.d/default.conf # new file with allow_anonymous false # disable anonymous user listener 1883 0.0.0.0 # open to all IP, open to localhost by default. password_file /etc/mosquitto/passwd # make password work sudo /etc/init.d/mosquitto restart` Test `mosquitto_sub -h localhost -u netro -P netrohome -t 'test' mosquitto_pub -h localhost -u netro -P netrohome -t 'test' -m 'hello'` Increase max open file limit issue `The default max open file is 1024, which may not be enough for large MQTT service, increase it to 65535 # vi /etc/systemd/system.conf DefaultLimitNOFILE=65536:524288 sudo systemctl daemon-reexec sudo /etc/init.d/mosquitto restart # cat /proc/<pid>/limits should be: Max open files 65535 524288 files # count the number of file opened by: sudo ls /proc/<pid>/fd \| wc -l`
10	LVM 空间跑哪里去了	安装ubuntu，默认LVM，全盘安装。但是装完发现只有100G，另外的130多G去哪里了？参见guide 扩展 `lvextend -l +100%FREE /dev/mapper/ubuntu--vg-ubuntu--lv resize2fs /dev/mapper/ubuntu--vg-ubuntu--lv`
9	undo remote commits in Git	undo remote commits: git reset --hard 'xxxxx' git clean -f -d git push -f
8	AWS Elastic IP	保留IP，最多5个这样EC2重启后IP地址不再变化有些区域的可以设定reverse DNS，对发送email有帮助
7	gio mount smb	guide `gio mount smb://<servername>/<sharename> # enter password # once the mount is created it will create a temporary path located at the following path, for example: # /run/user/1000/gvfs/smb-share\:server\=host.domain.com\,share\=files/ ln -s /run/user/<userid>/gvfs/smb-share\:server\=<servername>\,share\=<sharename>/ ~/<mountpoint>`
6	Ubuntu disable sleep	Disable LID close `sudo -H gedit /etc/systemd/logind.conf HandleLidSwitch=ignore sudo service systemd-logind restart # Still sleep after idle` UPower `sudoedit /etc/UPower/UPower.conf Change IgnoreLid to IgnoreLid=true service upower restart` `# also in /etc/systemd/logind.conf HandleLidSwitch=ignore HandleLidSwitchExternalPower=ignore HandleLidSwitchDocked=ignore HandleHibernateKey=ignore HandleSuspendKey=ignore IdleAction=ignore IdleActionSec=0 # Still sleep after idle` disable it via systemd `sudo systemctl mask sleep.target suspend.target hibernate.target hybrid-sleep.target`
5	内网穿透	路由器NAT映射端口，尝试并成功 ssh rdesktop smb
4	Basic HTTP File Server	python3 -m http.server
3	How do I resolve a ssh connection closed by remote host due to inactivity?	source Add to `.ssh/config` `TCPKeepAlive yes ServerAliveInterval 30` In command line `ssh -o TCPKeepAlive=yes user@some.host.com ssh -o ServerAliveInterval=30 user@some.host.com` TCPKeepAlive: This uses the KEEPALIVE option of the TCP/IP protocol to keep a connection alive after a specified interval of inactivity. On most systems, this means 2 hours. So, with the TCPKeepAlive option passed to SSH, the SSH client will send an encrypted packet to the SSH server, keeping your TCP connection up and running. ServerAliveInterval: This sets a timeout interval in seconds, which is specified by you, from which if no packets are sent from the SSH client to the SSH server, SSH will send an encrypted request to the server for a TCP response. To make that request every 30 seconds:
2	Mongo DB dump with compress and archive	source `mongodump --db country --gzip --archive=country.archive mongorestore --gzip --archive=country.archive` NOTE: The archive is mongo-specific format, can't be opened by other tools e.g. tar	mongodb
1	How to run a cron job using the sudo command	guide `sudo crontab -e @hourly rm somefile`

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Increase max open file limit issue