The Shar Pei, or Chinese Shar-Pei, is a breed of dog known for its distinctive features of deep wrinkles and a blue-black tongue. The breed comes from China. The name (沙皮, pinyin: shā pí; English name probably derived from British spelling of the Cantonese equivalent, sā pèih) translates to "sand skin" and refers to the texture of its short, rough coat. As puppies, Shar Pei have numerous wrinkles, but as they mature, these wrinkles loosen and spread out as they "grow into their skin". Shar Pei were named in 1978 as one of the world's rarest dog breeds by Time magazine and the Guinness Book of World Records, and the American Kennel Club did not recognize the breed until 1991.

Small, triangular ears, a muzzle shaped like that of a hippopotamus, and a high-set tail also give the Shar Pei a unique look. For show standard, "the tail is thick and round at the base, tapering to a fine point" (AKC standard February 28, 1998). As puppies, Shar peis are a lot more wrinkly than adults and, although some adults can be wrinklier than their puppy self, an adult pei should have wrinkles mostly on the face, a few on their shoulder and at the base of the tail.

In the Unix operating system, shar (an abbreviation of shell archive) is an archive format. A shar file is a shell script, and executing it will recreate the files. This is a type of self-extracting archive file. It can be created with the Unix shar utility. To extract the files, only the standard Unix Bourne shell sh is usually required.

Note that shar is not specified by the Single Unix Specification, so it is not formally a component of Unix, but a legacy utility.

While the shar format has the advantage of being plain text, it poses a risk due to being executable; for this reason the older and more general tar file format is usually preferred even for transferring text files. GNU provides its own version of shar in the GNU Sharutils collection.

unshar programs have been written for other operating systems but are not always reliable; shar files are shell scripts and can theoretically do anything that a shell script can do (including using incompatible features of enhanced or workalike shells), limiting their utility outside the Unix world.

PEI or Pei may refer to: