SSH

sshregex

SSHREGEX(1)                    SSH2                   SSHREGEX(1)


DESCRIPTION
       This  document describes the regular expressions (or glob-
       bing patterns) used in filename  globbing  with scpg3  and
       sftpg3  and  in  the sshd2_config and ssh-socks-proxy-con-
       fig.xml configuration files.

       Regex syntax used with scpg3 and sftpg3 is ZSH_FILEGLOB.


REGEX SYNTAX: EGREP
PATTERNS
       The escape character is a backslash '\'.  You can  use  it
       to escape meta characters to use them in their plain char-
       acter form.

       In the following examples literal 'E' and 'F'  denote  any
       expression, whether a pattern or a character.

       (      Start a capturing subexpression.

       )      End a capturing subexpression.

       E|F    Disjunction, match either E or F (inclusive).  E is
              preferred if both match.

       E*     Act as Kleene star, match E zero or more times.

       E+     Closure, match E one or more times.

       E?     Option, match E optionally once.

       .      Match any character except for  newline  characters
              (\n, \f, \r) and the NULL byte.

       E{n}   Match E exactly n times.

       E{n,} or E{n,0}
              Match E n or more times.

       E{,n} or E{0,n}
              Match E at most n times.

       E{n,m} Match  E  no  less  than n times and no more than m
              times.

       [      Start a character set. See section  CHARACTER  SETS
              FOR EGREP AND ZSH_FILEGLOB.

       $      Match  the  empty string at the end of the input or
              at the end of a line.

       ^      Match the empty string at the start of the input or
              at the beginning of a line.


ESCAPED TOKENS FOR REGEX SYNTAX EGREP
       \0n..n The literal byte with octal value n..n.

       \0     The NULL byte.

       \[1-9]..x
              The literal byte with decimal value [1-9]..x.

       \xn..n or \0xn..n
              The literal byte with hexadecimal value n..n.

       \<     Match  the empty string at the beginning of a word.

       \>     Match the empty string at the end of a word.

       \b     Match the empty string at a word boundary.

       \B     Match the empty string provided it is not at a word
              boundary.

       \w     Match  a  word-constituent character, equivalent to
              [a:zA:Z0:9-].

       \W     Match a non-word-constituent character.

       \a     Literal alarm character.

       \e     Literal escape character.

       \f     Literal line feed.

       \n     Literal new line, equivalent to C's \n so it can be
              more than one character long.

       \r     Literal carriage return.

       \t     Literal tab.

              All  other  escaped  characters  denote the literal
              character itself.


REGEX SYNTAX: ZSH_FILEGLOB (or TRADITIONAL)
PATTERNS
       The escape character is a backslash '\'.   With  this  you
       can  escape  meta  characters  to  use them in their plain
       character form.

       In the following examples literal 'E' and 'F'  denote  any
       expression, whether a pattern or a character.

       *      Match any string consisting of zero or more charac-
              ters.  The characters can be any  characters  apart
              from  slashes  (/).  However, the asterisk does not
              match a string if the string contains a dot (.)  as
              its  first  character,  or if the string contains a
              dot immediately after a slash.  This means that the
              asterisk  cannot  be  used  to match filenames that
              have a dot as their first character.

              If the previous character is a slash (/), or if  an
              asterisk  (*)  is  used  to  denote  a match at the
              beginning of a string, it does match a dot (.).

              That is, the asterisk (*) functions  as  normal  in
              Unix shell fileglobs.

       ?      Match  any single character except for a slash (/).
              However, do not match a dot (.) if located  at  the
              beginning of the string, or if the previous charac-
              ter is a slash (/).

              That is, the question mark (?) functions as  normal
              in  Unix shell fileglobs (at least in ZSH, although
              discarding the dot may not  be  a  standard  proce-
              dure).

       **/    Match  any  sequence  of  characters that is either
              empty, or ends in a slash.  However, the  substring
              '/.' is not allowed.  This mimics the **/ construct
              in ZSH.  (Please note that '**'  is  equivalent  to
              '*'.)

       E#     Act as Kleene star, match E zero or more times.

       E##    Closure, match E one or more times.

       (      Start a capturing subexpression.

       )      End a capturing subexpression.

       E|F    Disjunction, match either E or F (inclusive).  E is
              preferred if both match.

       [      Start a character set.  (see below)


CHARACTER SETS FOR EGREP AND ZSH_FILEGLOB
       A character set starts with '[' and  ends  at  non-escaped
       ']'  that  is  not part of a POSIX character set specifier
       and that does not follow immediately after '['.

       The following characters have a special meaning  and  need
       to be escaped if meant literally:


       - (minus sign)
              A  range  operator,  except  immediately after '[',
              where it loses its special meaning.

       ^ or ! (latter applies to ZSH_FILEGLOB)
              If immediately after the starting  '[',  denotes  a
              complement: the whole character set will be comple-
              mented.  Otherwise literal.  '^'.

       [:alnum:]
              Characters for which 'isalnum'  returns  true  (see
              ctype.h).

       [:alpha:]
              Characters  for  which  'isalpha' returns true (see
              ctype.h).

       [:cntrl:]
              Characters for which 'iscntrl'  returns  true  (see
              ctype.h).

       [:digit:]
              Characters  for  which  'isdigit' returns true (see
              ctype.h).

       [:graph:]
              Characters for which 'isgraph'  returns  true  (see
              ctype.h).

       [:lower:]
              Characters  for  which  'islower' returns true (see
              ctype.h).

       [:print:]
              Characters for which 'isprint'  returns  true  (see
              ctype.h).

       [:punct:]
              Characters  for  which  'ispunct' returns true (see
              ctype.h).

       [:space:]
              Characters for which 'isspace'  returns  true  (see
              ctype.h).

       [:upper:]
              Characters  for  which  'isupper' returns true (see
              ctype.h).

       [:xdigit:]
              Characters for which 'isxdigit' returns  true  (see
              ctype.h).


       EXAMPLE
              [[:xdigit:]XY]    is    typically   equivalent   to
              [0123456789ABCDEFabcdefXY] .


       It is also possible  to  include  the  predefined  escaped
       character sets into a newly defined one, so

           [\d\s]

       matches digits and whitespace characters.


REGEX SYNTAX: SSH
PATTERNS
       The  escape  character  is a tilde '~'.  With this you can
       escape meta characters to use them in their plain  charac-
       ter form.

       NOTE: In configuration the backslash '\' is used to escape
       the list separator (',').

       In the following examples literal 'E' and 'F'  denote  any
       expression, whether a pattern or a character.

       (      Start a capturing subexpression.

       )      End a capturing subexpression.

       {      Start anonymous, non-capturing subexpression.

       }      End anonymous, non-capturing subexpression.

       E|F    Disjunction, match either E or F (inclusive).  E is
              preferred if both match.

       E*     Act as Kleene star, match E zero or more times.

       E*?    Act as Kleene star, but  match  non-greedily  (lazy
              match).

       E+     Closure, match E one or more times.

       E+?    Closure, but match non-greedily (lazy match).

       E?     Option, match E optionally once.

       E??    Option, but match non-greedily (lazy match).

       .      Match  ANY  character,  including possibly the NULL
              byte and the newline characters.

       E/n/   Match E exactly n times.

       E/n,/ or E/n,0/
              Match E n or more times.

       E/,n/ or E/0,n/
              Match E at most n times.

       E/n,m/ Match E no less than n times and  no  more  than  m
              times.

       E/n,/? , E/n,0/? , E/,n/? , E/0,n/? , E/n,m/?
              The lazy versions of above.

       [      Start  a character set.  See section CHARACTER SETS
              FOR REGEX SYNTAX SSH.

       >C     One-character lookahead.  'C' must be either a lit-
              eral  character or parse as a character set.  Match
              the empty string anywhere provided  that  the  next
              character is 'C' or belongs to it.

       <C     One-character  lookback.  As above, but examine the
              previous character instead of the next character.

       $      Match the empty string at the end of the input.

       ^      Match the empty string at the start of the input.


ESCAPED TOKENS FOR REGEX SYNTAX SSH
       ~0n..n The literal byte with octal value n..n .

       ~0     The NULL byte.

       ~[1-9]..x
              The literal byte with decimal value [1-9]..x .

       ~xn..n or ~0xn..n
              The literal byte with hexadecimal value n..n .

       ~<     Match the empty string at the beginning of a  word.

       ~>     Match the empty string at the end of a word.

       ~b     Match the empty string at a word boundary.

       ~B     Match the empty string provided it is not at a word
              boundary.

       ~d     Match any digit, equivalent to [0:9].

       ~D     Match any character except a digit.

       ~s     Match a whitespace character (matches  space,  new-
              line,  line feed, carriage return, tab and vertical
              tab).

       ~S     Match a non-whitespace character.

       ~w     Match a word-constituent character,  equivalent  to
              [a:zA:Z0:9-].

       ~W     Match a non-word-constituent character.

       ~a     Literal alarm character.

       ~e     Literal escape character.

       ~f     Literal line feed.

       ~n     Literal new line, equivalent to C's \n so it can be
              more than one character long.

       ~r     Literal carriage return.

       ~t     Literal tab.


       All other escaped characters denote the literal  character
       itself.


CHARACTER SETS FOR REGEX SYNTAX SSH
       A  character  set  starts with '[' and ends at non-escaped
       ']' that is not part of a POSIX  character  set  specifier
       and that does not follow immediately after '['.

       The  following  characters have a special meaning and need
       to be escaped if meant literally:


       :      A range operator,  except  immediately  after  '[',
              where it loses its special meaning.

       - (minus sign)
              Until next +, the characters, ranges, and sets will
              be subtracted  from  the  current  set  instead  of
              adding.   If  appears  as the first character after
              '[', start subtracting from a  set  containing  all
              characters instead of the empty set.

       +      Until next -, the characters, ranges, and sets will
              be added to the current set.  This is the  default.

       [:alnum:]
              Characters  for  which  'isalnum' returns true (see
              ctype.h).

       [:alpha:]
              Characters for which 'isalpha'  returns  true  (see
              ctype.h).

       [:cntrl:]
              Characters  for  which  'iscntrl' returns true (see
              ctype.h).

       [:digit:]
              Characters for which 'isdigit'  returns  true  (see
              ctype.h).

       [:graph:]
              Characters  for  which  'isgraph' returns true (see
              ctype.h).

       [:lower:]
              Characters for which 'islower'  returns  true  (see
              ctype.h).

       [:print:]
              Characters  for  which  'isprint' returns true (see
              ctype.h).

       [:punct:]
              Characters for which 'ispunct'  returns  true  (see
              ctype.h).

       [:space:]
              Characters  for  which  'isspace' returns true (see
              ctype.h).

       [:upper:]
              Characters for which 'isupper'  returns  true  (see
              ctype.h).

       [:xdigit:]
              Characters  for  which 'isxdigit' returns true (see
              ctype.h).


       It is also possible  to  include  the  predefined  escaped
       character sets into a newly defined one, so

           [~d~s]

       matches digits and whitespace characters.

       Also,  escape  sequences resulting in literals work inside
       character sets.


       EXAMPLE
              [[:xdigit:]-a:e]   is   typically   equivalent   to
              [0123456789ABCDEFf] .


AUTHORS
       SSH Communications Security Corporation

       For more information, see http://www.ssh.com.


SEE ALSO
       sshd2_config(5), ssh-broker-config(5), scpg3(1), sftpg3(1)