ax_normalize_path

Synopsis

AX_NORMALIZE_PATH(VARNAME, [REFERENCE_STRING])

Description

Perform some cleanups on the value of $VARNAME (interpreted as a path):

  - empty paths are changed to '.'
  - trailing slashes are removed
  - repeated slashes are squeezed except a leading doubled slash '//'
    (which might indicate a networked disk on some OS).

REFERENCE_STRING is used to turn ’/’ into ’\’ and vice-versa: if REFERENCE_STRING contains some backslashes, all slashes and backslashes are turned into backslashes, otherwise they are all turned into slashes.

This makes processing of DOS filenames quite easier, because you can turn a filename to the Unix notation, make your processing, and turn it back to original notation.

  filename='A:\FOO\\BAR\'
  old_filename="$filename"
  # Switch to the unix notation
  AX_NORMALIZE_PATH([filename], ["/"])
  # now we have $filename = 'A:/FOO/BAR' and we can process it as if
  # it was a Unix path.  For instance let's say that you want
  # to append '/subpath':
  filename="$filename/subpath"
  # finally switch back to the original notation
  AX_NORMALIZE_PATH([filename], ["$old_filename"])
  # now $filename equals to 'A:\FOO\BAR\subpath'

One good reason to make all path processing with the unix convention is that backslashes have a special meaning in many cases. For instance

  expr 'A:\FOO' : 'A:\Foo'

will return 0 because the second argument is a regex in which backslashes have to be backslashed. In other words, to have the two strings to match you should write this instead:

  expr 'A:\Foo' : 'A:\\Foo'

Such behavior makes DOS filenames extremely unpleasant to work with. So temporary turn your paths to the Unix notation, and revert them to the original notation after the processing. See the macro AX_COMPUTE_RELATIVE_PATHS for a concrete example of this.

REFERENCE_STRING defaults to $VARIABLE, this means that slashes will be converted to backslashes if $VARIABLE already contains some backslashes (see $thirddir below).

  firstdir='/usr/local//share'
  seconddir='C:\Program Files\\'
  thirddir='C:\home/usr/'
  AX_NORMALIZE_PATH([firstdir])
  AX_NORMALIZE_PATH([seconddir])
  AX_NORMALIZE_PATH([thirddir])
  # $firstdir = '/usr/local/share'
  # $seconddir = 'C:\Program Files'
  # $thirddir = 'C:\home\usr'

Source Code

Download the latest version of ax_normalize_path.m4 or browse the macro’s revision history.

License

Copyright © 2008 Alexandre Duret-Lutz adl@gnu.org

This program is free software; you can redistribute it and/or modify it under the terms of the GNU General Public License as published by the Free Software Foundation; either version 2 of the License, or (at your option) any later version.

This program is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for more details.

You should have received a copy of the GNU General Public License along with this program. If not, see <https://www.gnu.org/licenses/>.

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