ladybird/Meta/write-only-on-difference.sh
joshua stein 0d215b5548 Build: Sprinkle some portability, fix on OpenBSD
realpath(1) is specific to coreutils and its behavior can be had
with readlink -f

Create the Toolchain Build directory if it doesn't exist before
calling readlink, since realpath(3) on at least OpenBSD will error
on a non-existent path
2021-02-14 09:29:22 +01:00

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#!/bin/sh
set -e
if [ "$#" -lt "2" ]; then
echo "USAGE: $0 <file> <cmd...>"
exit 1
fi
DST_FILE="$1"
shift
# Just in case:
mkdir -p -- "$(dirname -- "${DST_FILE}")"
cleanup()
{
rm -f -- "${DST_FILE}.tmp"
}
trap cleanup 0 1 2 3 6
"$@" > "${DST_FILE}.tmp"
# If we get here, the command was successful, and we can overwrite the destination.
if ! cmp -s -- "${DST_FILE}.tmp" "${DST_FILE}"; then
# File changed, need to overwrite:
mv -f -- "${DST_FILE}.tmp" "${DST_FILE}"
fi