Running lz4 --quiet --keep input.file.txt will produce input.file.txt.lz4 lz4 --quiet --keep input.file.txt >/dev/null will instead print this on stderr: Warning : using stdout as default output. Do not rely on this behavior: use explicit `-c` instead ! and produces no compressed file. This is behaviour different than all compression tools (gzip, bzip2, lzma, xz, brotli, arj, 7z, zip, cab, snappy, zstd, ...). Stdout should only be used when `-c` is expliclty passed, or the input is the stdout (i.e. foo | lz4 | ...). Regards, Witold