Pure bash
, no basename
, no variable juggling. Set a string and echo
:
p=/the/path/foo.txt
echo "${p//+(*\/|.*)}"
Output:
foo
Note: the bash
extglob option must be "on", (Ubuntu sets extglob "on" by default), if it's not, do:
shopt -s extglob
Walking through the ${p//+(*\/|.*)}
:
${p
-- start with $p.//
substitute every instance of the pattern that follows.+(
match one or more of the pattern list in parenthesis, (i.e. until item #7 below).*\/
matches anything before a literal "/
" char. |
which in this instance acts like a logical OR..*
matches anything after a literal ".
" -- that is, in bash
the ".
" is just a period char, and not a regex dot.)
end pattern list.}
end parameter expansion. With a string substitution, there's usually another /
there, followed by a replacement string. But since there's no /
there, the matched patterns are substituted with nothing; this deletes the matches.Relevant man bash
background:
${parameter/pattern/string} Pattern substitution. The pattern is expanded to produce a pat tern just as in pathname expansion. Parameter is expanded and the longest match of pattern against its value is replaced with string. If pattern begins with /, all matches of pattern are replaced with string. Normally only the first match is replaced. If pattern begins with #, it must match at the begin- ning of the expanded value of parameter. If pattern begins with %, it must match at the end of the expanded value of parameter. If string is null, matches of pattern are deleted and the / fol lowing pattern may be omitted. If parameter is @ or *, the sub stitution operation is applied to each positional parameter in turn, and the expansion is the resultant list. If parameter is an array variable subscripted with @ or *, the substitution operation is applied to each member of the array in turn, and the expansion is the resultant list.
If the extglob shell option is enabled using the shopt builtin, several extended pattern matching operators are recognized. In the following description, a pattern-list is a list of one or more patterns separated by a |. Composite patterns may be formed using one or more of the fol lowing sub-patterns: ?(pattern-list) Matches zero or one occurrence of the given patterns *(pattern-list) Matches zero or more occurrences of the given patterns +(pattern-list) Matches one or more occurrences of the given patterns @(pattern-list) Matches one of the given patterns !(pattern-list) Matches anything except one of the given patterns