commit: 3ade2ff3c0d3f603f0b92ba72fc6b2d44a63ac92
parent 5f710b994abe117862214072869e78f54ee950b7
Author: Haelwenn (lanodan) Monnier <contact@hacktivis.me>
Date: Tue, 15 Oct 2024 13:45:49 +0200
cmd/chmod: detail the symbolic operations grammar in BNF-style
Diffstat:
| M | cmd/chmod.1 | 73 | ++++++++++++++++++++++++++++++++++++++++++++++++++++++------------------- |
1 file changed, 54 insertions(+), 19 deletions(-)
diff --git a/cmd/chmod.1 b/cmd/chmod.1
@@ -44,27 +44,60 @@ Verbose, print both changes and retained modes
.Ar file
.El
.Sh SYMBOLIC OPERATIONS
-Roughly corresponds to the following regex:
-.Ql ((^|,)[ugoa]*([+-=][ugo]|[+-=][rwxXst]+)+)+
-.Bl -tag -width Ds
-.It ,
-Separator between each operation,
+Uses the following grammar:
+.Bd -literal
+mode ::= clause [',' clause]*
+clause ::= who* action+
+action ::= [op | op perm+ | op permcopy]
+
+who ::= 'u' | 'g' | 'o' | 'a'
+op ::= '+' | '-' | '='
+perm ::= 'r' | 'w' | 'x' | 'X' | 's' | 't'
+
+permcopy ::= 'u' | 'g' | 'o'
+.Ed
+.Pp
+Which corresponds to:
+.Bl -tag -width permcopy
+.It mode
+List of
+.Ql clause
+to apply, each separated by a comma.
+.Pp
+For example
.Ql g+r,o=g
-sets read for group and copies to other the resulting permissions of group.
-.It [ugoa]
-who: Sets who to assign permissions to.
-.It [+-=]
-op: Respectively add(+), del(-), set(=).
+sets read permission for group part and copies to other part the resulting permissions of the group part.
+.It clause
+Optionally starts with
+.Ql who
+and contains one or more
+.Ql action .
.Pp
-When who isn't given,
+When
+.Ql who
+isn't given,
.Xr umask 3
is followed similarly to file creation.
-When neither permcopy nor permlist is given, set(=) clears all permissions.
-.It [ugo]
-permcopy: Sets who to copy permissions from.
-.It [rwxXst]+
-permlist: Sets which permissions to assign, respectively:
-.Bl -tag -width X
+.It action
+Always starts with
+.Ql op ,
+optionally followed by either one or more
+.Ql perm ,
+or a single
+.Ql permcopy
+.It who
+user(u), group(g), other(o), all(a)
+.It op
+Operation to apply: add(+), del(-), set(=)
+.Pp
+When neither
+.Ql perm
+nor
+.Ql permcopy
+were given, set(=) clears all permissions.
+.It perm
+which permissions to assign:
+.Bl -tag -width X -compact
.It r
Read
.It w
@@ -74,10 +107,12 @@ Execute/Search
.It X
Search (directories-only)
.It s
-Setuid when assigned to user, setgid when assigned to group.
+Setuid when assigned to user, setgid when assigned to group
.It t
-Sticky bit.
+Sticky bit
.El
+.It permcopy
+who to copy permissions from: user(u), group(g), other(o)
.El
.Sh EXIT STATUS
.Ex -std
