UNZIP Options: M, n, N, o, P, q, S

the originating file system. -M pipe all output through an internal pager similar to the Unix more(1) command. At the end of a screenful of output, unzip pauses with a ‘‘--More--’’ prompt; the next screenful may be viewed by pressing the Enter (Return) key or the space bar. un‐ zip can be terminated by pressing the ‘‘q’’ key and, on some sys‐ tems, the Enter/Return key. Unlike Unix more(1), there is no forward‐searching or editing capability. Also, unzip doesn’t no‐ tice if long lines wrap at the edge of the screen, effectively resulting in the printing of two or more lines and the likelihood that some text will scroll off the top of the screen before being viewed. On some systems the number of available lines on the screen is not detected, in which case unzip assumes the height is 24 lines. -n never overwrite existing files. If a file already exists, skip the extraction of that file without prompting. By default unzip queries before extracting any file that already exists; the user may choose to overwrite only the current file, overwrite all files, skip extraction of the current file, skip extraction of all existing files, or rename the current file. -N [Amiga] extract file comments as Amiga filenotes. File comments are created with the -c option of zip(1), or with the -N option of the Amiga port of zip(1), which stores filenotes as comments. -o overwrite existing files without prompting. This is a dangerous option, so use it with care. (It is often used with -f, however, and is the only way to overwrite directory EAs under OS/2.) -P password use password to decrypt encrypted zipfile entries (if any). THIS IS INSECURE! Many multi‐user operating systems provide ways for any user to see the current command line of any other user; even on stand‐alone systems there is always the threat of over‐the‐ shoulder peeking. Storing the plaintext password as part of a command line in an automated script is even worse. Whenever pos‐ sible, use the non‐echoing, interactive prompt to enter pass‐ words. (And where security is truly important, use strong en‐ cryption such as Pretty Good Privacy instead of the relatively weak encryption provided by standard zipfile utilities.) -q perform operations quietly (-qq = even quieter). Ordinarily un‐ zip prints the names of the files it’s extracting or testing, the extraction methods, any file or zipfile comments that may be stored in the archive, and possibly a summary when finished with each archive. The -q[q] options suppress the printing of some or all of these messages. -s [OS/2, NT, MS‐DOS] convert spaces in filenames to underscores. Since all PC operating systems allow spaces in filenames, unzip by default extracts filenames with spaces intact (e.g., ‘‘EA DATA. SF’’). This can be awkward, however, since MS‐DOS in particular does not gracefully support spaces in filenames. Con‐ version of spaces to underscores can eliminate the awkwardness in some cases. -S [VMS] convert text files (-a, -aa) into Stream_LF record format, instead of the text‐file default, variable‐length record format. (Stream_LF is the default record format of VMS unzip. It is ap‐ plied unless conversion (-a, -aa and/or

This section describes the functionality of UNZIP options. `-M` pipes output through an internal pager, pausing at each screenful. `-n` prevents overwriting existing files. `-N` (Amiga) extracts file comments as Amiga filenotes. `-o` overwrites existing files without prompting. `-P` uses a password to decrypt encrypted entries (insecure, use with caution). `-q` operates quietly, suppressing messages. `-S` (VMS) converts text files to Stream_LF record format.