如何编写bash脚本来检查程序或库是否存在

#!/bin/bash

check_program() {
    program_name=$1
    which $program_name >/dev/null 2>&1
    if [ $? -eq 0 ]; then
        echo "$program_name is installed."
    else
        echo "$program_name is not installed."
    fi
}

check_library() {
    library_name=$1
    if dpkg-query -l $library_name >/dev/null 2>&1 || rpm -q $library_name >/dev/null 2>&1; then
        echo "$library_name is installed."
    else
        echo "$library_name is not installed."
    fi
}

# 检查程序
check_program "gcc"
check_program "python"

# 检查库
check_library "libssl-dev"
check_library "libmysqlclient-dev"