Tips in Linux

概览：

• Clear apt cache
• 镜像源公钥安装
• 获取CPU总核心数
• Linux Console 默认信息
• shell script check permission
  • Makefile help menu

Clear apt cache

sudo rm -v /var/cache/apt/archives/*.deb

镜像源公钥安装

sudo apt-key adv --keyserver keyserver.ubuntu.com --recv-keys # + 公钥名

获取CPU总核心数

echo $(grep -c ^processor /proc/cpuinfo 2>/dev/null)
# use
make -j $(grep -c ^processor /proc/cpuinfo 2>/dev/null)

Linux Console 默认信息

/etc/issue
/etc/update-motd.d/*
/run/motd.dynamic

shell script check permission

if [ $(id -u) -ne 0 ]; then
  printf "Script must be run as root\n"
  exit 1
fi

Makefile help menu

all: help

.PHONY: help
help:          ## Show this help.
	@fgrep -h "##" $(MAKEFILE_LIST) | fgrep -v fgrep | sed -e 's/\\$$//' | sed -e 's/##//'