Re^2: Huge files manipulation

[graff]

Unix and gnu sort rely on having an adequate amount of available disk space on /tmp; if the OP is using a machine with insufficient free space on /tmp,  sort -u will fail.

[JavaFan]

Only if you haven't told sort if can use another directory. (GNU) sort will either use the directory given with the -T option, the directory in the TMPDIR environment variable, or /tmp. In that order. The POSIX standard mentions that -T is undocumented, but existing in some implementations, and it encourages implementors to support the TMPDIR environment variable.