我正在Ubuntu系统上工作，目前我正在做的是:
if ! which command > /dev/null; then
echo -e "Command not found! Install? (y/n) \c"
read
if "$REPLY" = "y"; then
sudo apt-get install command
fi
fi
大多数人都会这么做吗?还是有更优雅的解决方案?
当前回答
现在apt-get似乎有一个选项——不升级，只做OP想要的:
——no-upgrade不升级包。当与install一起使用时，no-upgrade将阻止已经安装的包被升级。
Manpage来自https://linux.die.net/man/8/apt-get
因此你可以使用
apt-get install --no-upgrade package
如果不是，包才会被安装。
其他回答
有点以你的为基础，只是更“优雅”一点。只是因为我很无聊。
#!/bin/bash
FOUND=("\033[38;5;10m")
NOTFOUND=("\033[38;5;9m")
PKG="${@:1}"
command ${PKG} &>/dev/null
if [[ $? != 0 ]]; then
echo -e "${NOTFOUND}[!] ${PKG} not found [!]"
echo -e "${NOTFOUND}[!] Would you like to install ${PKG} now ? [!]"
read -p "[Y/N] >$ " ANSWER
if [[ ${ANSWER} == [yY] || ${ANSWER} == [yY][eE][sS] ]]; then
if grep -q "bian" /etc/os-release; then
sudo apt-get install ${PKG}
elif grep -q "arch" /etc/os-release; then
if [[ -f /bin/yay ]] || [[ -f /bin/yaourt ]]; then
yaourt -S ${PKG} 2>./err || yay -S ${PKG} 2>./err
else
sudo pacman -S ${PKG}
fi
elif grep -q "fedora" /etc/os-release; then
sudo dnf install ${PKG}
else
echo -e "${NOTFOUND}[!] This script couldn't detect your package manager [!]"
echo -e "${NOTFOUND}[!] Manually install it [!]"
fi
elif [[ ${ANSWER} == [nN] || ${ANSWER} == [nN][oO] ]]; then
echo -e "${NOTFOUND}[!] Exiting [!]"
fi
else
echo -e "${FOUND}[+] ${PKG} found [+]"
fi
要检查是否安装了packagename，输入:
dpkg -s <packagename>
您还可以使用dpkg-query，它的输出更简洁，而且还接受通配符。
dpkg-query -l <packagename>
要找到哪个包拥有该命令，请尝试:
dpkg -S `which <command>`
有关更多详细信息，请参见文章“了解Linux中是否安装了软件包”和dpkg备忘单。
which <command>
if [ $? == 1 ]; then
<pkg-manager> -y install <command>
fi
这个特性已经存在于Ubuntu和Debian的command-not-found包中。
这个命令是最容易记住的:
dpkg --get-selections <package-name>
如果已经安装，它会打印:
<包名称>安装
否则它会打印
没有找到匹配<package-name>的包。
这是在Ubuntu 12.04.1 (Precise穿山甲)上测试的。
