A quick set of (almost) one-liner functions to retrieve a Liux/BSD computer's specifications from the shell.

computer_specs.sh

#
# Distro name
#

# Ubuntu / Debian
if [ -e /etc/lsb-release ]; then
	. /etc/lsb-release
	distro="$DISTRIB_ID $DISTRIB_RELEASE $DISTRIB_CODENAME"

# RedHat / Fedora / CentOS
elif [ -e /etc/redhat-release ]; then distro=$(cat /etc/redhat-release)
elif [ -e /etc/system-release ]; then distro=$(cat /etc/system-release)

# Arch Linux / Manjaroo
elif [ -e /etc/os-release ]; then
	. /etc/os-release
	distro="$NAME"

# Fallback
else
	distro="Linux generic"
fi


#
# Kernel / Memory / CPU details
#

kernel="$(uname -m) $(uname -sr)"


meminfo=( $(IFS=$'\n' sed -nE '
	s/MemTotal:\s+([0-9]+) kB/\1/p
	s/MemFree:\s+([0-9]+) kB/\1/p
	s/MemAvailable:\s+([0-9]+) kB/\1/p
' /proc/meminfo) )

mem_total_kb="${meminfo[1]}"; mem_total_mb=$(( $mem_total_kb / 1024 ))
mem_free_kb="${meminfo[2]}";  mem_free_mb=$(( $mem_free_kb / 1024 ))
mem_avail_kb="${meminfo[3]}"; mem_avail_mb=$(( $mem_avail_kb / 1024 ))


cpu_name=$(sed -nE '8q; s/model name\s*:\s+([A-Za-z0-9 \-\(\)]+)/\1/p' /proc/cpuinfo)
cpu_cores=$(sed -nE '8q; s/cpu cores\s*:\s+([A-Za-z0-9 \-\(\)]+)/\1/p' /proc/cpuinfo)
cpu_threads=$(sed -nE '12q; s/siblings\s*:\s+([A-Za-z0-9 \-\(\)]+)/\1/p' /proc/cpuinfo)

cpu_freq=$(cat /sys/devices/system/cpu/cpufreq/policy0/cpuinfo_max_freq)
cpu_freq="${cpu_freq:0:1}.${cpu_freq:1:1}"


#
# Other
#

case $SHELL in
	*zsh)  shell=$($SHELL --version | sed -E 's/(\(.*\))//');;
	*bash) shell=$($SHELL --version | sed -E '1q');;
	*)     shell="Unknown";;
esac


disks_raw=( $(df -Ph --total --local -x tmpfs -x devtmpfs) )
disks_total=${disks_raw[-5]}
disks_used=${disks_raw[-4]}
disks_avail=${disks_raw[-3]}

if [ -e /bin/glxinfo ] || [ -e /usr/bin/glxinfo ]
then
	IFS=$'\n' glxinfo=( $( glxinfo -B | sed -nE "
		s|OpenGL vendor string: (.*)|\1|pg
		s|OpenGL renderer string: ([^/]+).*|\1|pg
	") )
	
	gpu_vendor="${glxinfo[1]}"
	gpu_device="${glxinfo[2]}"

	# Avoid "Intel Open Source Technology Center"
	case "$gpu_vendor" in
		Intel*)	gpu="Intel $gpu_device";;
		NVIDIA*) gpu="$gpu_vendor $gpu_device";;
	esac
else
	# Change IFS to match only newlines in lspci
	IFS=$'\n' gpu_all=( $( \
		lspci -mm | sed -nE '/VGA/{ s/(" "| "|" )/|/g; s/"$//p }'
	) )

	# Internal GPU (iGPU)
	IFS=$'|' gpu_int=( $(echo ${gpu_all[1]}) )
	gpu_int="${gpu_int[3]} $(echo "${gpu_int[4]}" | sed -nE 's/\[(.*)\]/\1/p')"

	# External GPU (graphics card)
	IFS=$'|' gpu_ext=( $(echo ${gpu_all[2]}) )
	gpu_ext="${gpu_ext[3]} $(echo "${gpu_ext[4]}" | sed -nE 's/\[(.*)\]/\1/p')"

	# Prefer external gpu
	gpu="${gpu_ext:-gpu_int}"
fi

Note: this tool has been enhanced a lot and is now available here: https://github.com/SamantazFox/Sam-Shell-Scripts/tree/master/nanofetch