Best effort dependency resolution

Add a new check_install function that checks if a tool is installed and
tries to install it on a best effort basic. Modify all scripts that
benefit from it. Small indentation and correctness fixes.

	modified:   functions/7za.fish
	modified:   functions/alert.fish
	new file:   functions/check_install.fish
	modified:   functions/lscmd.fish
	modified:   functions/rchmod.fish
	modified:   functions/renlow.fish
	modified:   functions/rlsxattr.fish
	modified:   functions/rsdos.fish
	modified:   functions/rsmac.fish
	modified:   functions/rsxattr.fish
	modified:   functions/uz.fish

1 files changed, 2 insertions, 7 deletions

diff --git a/functions/rsxattr.fish b/functions/rsxattr.fish
index 7003879..bd1456e 100644
--- a/functions/rsxattr.fish
+++ b/functions/rsxattr.fish
@@ -1,16 +1,11 @@
 function rsxattr --description 'Recursively delete all user xattrs'
 
-if not command -sq 'getfattr'; and command -sq 'setfattr'
+if not check_install 'getfattr' 'attr'
   echo "Can't find xattr tools."
   return 1
 end
 
-if not command -sq 'sed'
-  echo "Can't find sed."
-  return 1
-end
-
-if not command -sq 'awk'
+if not check_install 'awk' 'gawk'
   echo "Can't find awk."
   return 1
 end