I was asked by on co-worker that he can not gzunzip a file ,he got error messages like:

gunzip filename.gz has 1 other link -- unchanged


gunzip -f file.gz

Use option “-f” to force decompression.

Wait ,but why

Below snippet from gzip man page tells the reason

-- has xx other links: unchanged
              The input file has links; it is left unchanged.  See ln(1) for more information. Use the -f flag to force
              compression of multiply-linked files

How to reproduce the error

Below commands reproduce this error , for gunzip should be the same

j@ubuntu:~/tmp$ touch file1
j@ubuntu:~/tmp$ ln file1 file2
j@ubuntu:~/tmp$ gzip file1
gzip: file1 has 1 other link  -- unchanged
j@ubuntu:~/tmp$ gzip -f file1
j@ubuntu:~/tmp$ ls
file1.gz  file2