Combine 2 PDFS of (potentially) different scales

cat-and-scale-pdfs.shq

#! /bin/bash

A="a.pdf"
B="b.pdf"

DATE=$(date '+%Y-%m-%d')

OUTFILE="combined-$DATE.pdf"

# Get the page size from each pdf A and B
A_DIMS=$(pdfinfo $A | grep "Page size" | tr -s ' ' | cut -d" " -f"3,5")
B_DIMS=$(pdfinfo $B | grep "Page size" | tr -s ' ' | cut -d" " -f"3,5")
# Get the integer part of each height and width.
A_DIM_WIDTH=$(echo $A_DIMS | cut -d" " -f1)
A_DIM_HEIGHT=$(echo $A_DIMS | cut -d" " -f2)
B_DIM_WIDTH=$(echo $B_DIMS | cut -d" " -f1)
B_DIM_HEIGHT=$(echo $B_DIMS | cut -d" " -f2)

# Get the minimum width
TARGET_WIDTH=$A_DIM_WIDTH
if (( $(echo "$A_DIM_WIDTH > $B_DIM_WIDTH" |bc -l) )); then
    TARGET_WIDTH=$B_DIM_WIDTH
fi
# Calculate the appropriate height based on the aspect ratio of each slide.
TARGET_HEIGHT_A=$(echo "$TARGET_WIDTH*($A_DIM_HEIGHT/$A_DIM_WIDTH)" | bc -l)
TARGET_HEIGHT_B=$(echo "$TARGET_WIDTH*($B_DIM_HEIGHT/$B_DIM_WIDTH)" | bc -l)

# Scale each pdf to temp
SCALED_A="scaled_$A"
SCALED_B="scaled_$B"

# -sPAPERSIZE=a4
gs -o "$SCALED_A" -sDEVICE=pdfwrite -dDEVICEWIDTHPOINTS=$TARGET_WIDTH -dDEVICEHEIGHTPOINTS=$TARGET_HEIGHT_A -dFIXEDMEDIA -dPDFFitPage -dCompatibilityLevel=1.4 "$A"
gs -o "$SCALED_B" -sDEVICE=pdfwrite -dDEVICEWIDTHPOINTS=$TARGET_WIDTH -dDEVICEHEIGHTPOINTS=$TARGET_HEIGHT_B -dFIXEDMEDIA -dPDFFitPage -dCompatibilityLevel=1.4 "$B"

# Cat the files.
gs -dBATCH -dNOPAUSE -q -sDEVICE=pdfwrite -dPDFSETTINGS=/printer -sOutputFile="$OUTFILE" "$SCALED_A" "$SCALED_B"