ladybird/Meta/write-only-on-difference.sh

#!/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
Meta: Provide a way to only update a file if the output changes This is only useful for build commands that update their destination in all cases and thus sometimes confuse cmake into rebuilding everything needlessly. 2020-08-02 20:05:45 +00:00			`#!/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.`

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 2020-12-28 23:36:15 +00:00			`if ! cmp -s -- "${DST_FILE}.tmp" "${DST_FILE}"; then`
Meta: Provide a way to only update a file if the output changes This is only useful for build commands that update their destination in all cases and thus sometimes confuse cmake into rebuilding everything needlessly. 2020-08-02 20:05:45 +00:00			`# File changed, need to overwrite:`
			`mv -f -- "${DST_FILE}.tmp" "${DST_FILE}"`
			`fi`