Add some command into startup process
sudo vim /etc/systemd/system/rc-local.service
[Unit]Description=/etc/rc.local CompatibilityConditionPathExists=/etc/rc.local
[Service]Type=forkingExecStart=/etc/rc.local startTimeoutSec=0StandardOutput=ttyRemainAfterExit=yesSysVStartPriority=99
[Install]WantedBy=multi-user.targetsudo vim /etc/rc.local
#!/bin/bash
dhclient
service ssh restart
service smbd restart
mount /dev/sdb1 /mnt/disk16t
exit 0sudo chmod +x /etc/rc.localsudo systemctl start rc-local
sudo systemctl enable rc-localsudo reboot
Wait so long to connect network when startup process
cd /etc/systemd/system/network-online.target.wants/more systemd-networkd-wait-online.service
# SPDX-License-Identifier: LGPL-2.1-or-later
#
# This file is part of systemd.
#
# systemd is free software; you can redistribute it and/or modify it
# under the terms of the GNU Lesser General Public License as published by
# the Free Software Foundation; either version 2.1 of the License, or
# (at your option) any later version.[Unit]
Description=Wait for Network to be Configured
Documentation=man:systemd-networkd-wait-online.service(8)
DefaultDependencies=no
Conflicts=shutdown.target
Requires=systemd-networkd.service
After=systemd-networkd.service
Before=network-online.target shutdown.target[Service]
Type=oneshot
ExecStart=/lib/systemd/systemd-networkd-wait-online
RemainAfterExit=yesTimeoutStartSec=2sec[Install]
WantedBy=network-online.target
How to fix ip address
more /etc/netplan/00-installer-config.yaml
# This is the network config written by 'subiquity'
network:ethernets:eno1np0:dhcp4: noaddresses:- 10.18.57.25/24gateway4: 10.18.57.255nameservers:addresses: [8.8.8.8, 4.4.4.4]eno2np1:dhcp4: trueversion: 2
Makeup U boot ubuntu
download u tools: http://rufus.ie/downloads/
Ubuntu image mirror: https://launchpad.net/ubuntu/+cdmirrors
Linux change passwd
passwd
sudo passwd root
How to get core dump file
cat /proc/sys/kernel/core_pattern
echo core > /proc/sys/kernel/core_pattern
uclimit -c unlimited
Linux doesn’t suspend after close LID
sudo vim /etc/systemd/logind.conHandleLidSwitch=ignoreHandleLidSwitchExternalPower=ignoreHandleLidSwitchDocker=ignore
sudo systemctl restart systemd-logind
SSH
Serversudo apt install openssl-serversudo /etc/init.d/ssh restart
clientssh username@ipaddress
SAMBA
Linuxsudo apt install sambasudo vim /etc/samba/smb.conf[jow]comment = jow share folderpath = /home/jowbrowseable = yesread only = nosudo smbpasswd -a jowsudo smbpasswd -e jowsudo /etc/init.d/smbd restart
Windowsright click mycomputer ===> mapping driver device ===> fill \\linuxIpAddress\jow
grep awd sed
find /usr -name *.c -or -name *.h
find /usr -name *.c -and -name main*.c
find /usr -name *.txt | xargs grep -Rni "Hello*.world"
grep -Rni "Hello*.world"
ls -l | awk '{print $1}'
sed -i "s|subproject(|# subproject(|" meson.build
sed -i '/gn_args_args = list/i \ \ \ \ \ \ \ \ \ \ \ \ \ \ gn_args["external_cxxflags"] += [self._generate_gitmsg()]' build.py
Usb serial device response slowly
WindowsFind the device from device manager.right click ===> advanced ===> delay counter ===> default is 16ms, change to be 1ms
Linuxssudo -icat /sys/bus/usb-serial/devices/ttyUSB0/latency_timerecho 1 > /sys/bus/usb-serial/devices/ttyUSB0/latency_timer
