커널소스를 분석해 보진 않아서 정확하게 어떻게 여는지는 모르겠지만,
아마 tty 특성상 canonical mode로 여는것으로 보인다.
/dev/console is a symbolic link to /dev/tty0,
and the kernel regards /dev/tty0 as a synonym for the current VT.
XFree86 1.3 changes the owner of /dev/tty0, but does not reset this
after finishing. Thus, loadkeys or dumpkeys might fail because
someone else owns /dev/tty0;
in such a case you might run X first.
Note that you cannot change keyboard mappings when not at the console
-u Use the unified output format.
-r When comparing directories, recursively compareany subdirectories found.
-N
--new-file
In directory comparison, if a file is found in only one directory, treat it as present but empty in the
other directory.
일반적으로 GNU 프로젝트의 패치로 사용하는 옵션이라고 한다.
-u는 unified 포맷 출력
-r은 디렉토리 비교
-N은 새 파일이 있을시 없는쪽은 비어있는 파일로 간주하고 비교함
간단하게 전부 내용이 추가된걸로 표시된다. 이러한 옵션 없이 diff하면 아래와 같이 빈 파일이 출력된다.
Only in linux-2.6.17.14_stm22_0039_STFAE: .config2
DESCRIPTION
In the simplest case, diff compares the contents of the two files from-file and to-file. A file name of - stands
for text read from the standard input. As a special case, diff - - compares a copy of standard input to itself.
If from-file is a directory and to-file is not, diff compares the file in from-file whose file name is that of
to-file, and vice versa. The non-directory file must not be -.
If both from-file and to-file are directories, diff compares corresponding files in both directories, in alpha-
betical order; this comparison is not recursive unless the -r or --recursive option is given. diff never com-
pares the actual contents of a directory as if it were a file. The file that is fully specified may not be stan-
dard input, because standard input is nameless and the notion of ‘‘file with the same name’’ does not apply.
diff options begin with -, so normally from-file and to-file may not begin with -. However, -- as an argument by
itself treats the remaining arguments as file names even if they begin with -.
Options
Below is a summary of all of the options that GNU diff accepts. Most options have two equivalent names, one of
which is a single letter preceded by -, and the other of which is a long name preceded by --. Multiple single
letter options (unless they take an argument) can be combined into a single command line word: -ac is equivalent
to -a -c. Long named options can be abbreviated to any unique prefix of their name. Brackets ([ and ]) indicate
that an option takes an optional argument.
-lines Show lines (an integer) lines of context. This option does not specify an output format by itself; it has
no effect unless it is combined with -c or -u. This option is obsolete. For proper operation, patch typ-
ically needs at least two lines of context.
-a Treat all files as text and compare them line-by-line, even if they do not seem to be text.
-b Ignore changes in amount of white space.
-B Ignore changes that just insert or delete blank lines.
--brief
Report only whether the files differ, not the details of the differences.
-c Use the context output format.
-C lines
--context[=lines]
Use the context output format, showing lines (an integer) lines of context, or three if lines is not
given. For proper operation, patch typically needs at least two lines of context.
--changed-group-format=format
Use format to output a line group containing differing lines from both files in if-then-else format.
-d Change the algorithm to perhaps find a smaller set of changes. This makes diff slower (sometimes much
slower).
-D name
Make merged if-then-else format output, conditional on the preprocessor macro name.
-e
--ed Make output that is a valid ed script.
--exclude=pattern
When comparing directories, ignore files and subdirectories whose basenames match pattern.
--exclude-from=file
When comparing directories, ignore files and subdirectories whose basenames match any pattern contained in
file.
--expand-tabs
Expand tabs to spaces in the output, to preserve the alignment of tabs in the input files.
-f Make output that looks vaguely like an ed script but has changes in the order they appear in the file.
-F regexp
In context and unified format, for each hunk of differences, show some of the last preceding line that
matches regexp.
--forward-ed
Make output that looks vaguely like an ed script but has changes in the order they appear in the file.
-h This option currently has no effect; it is present for Unix compatibility.
-H Use heuristics to speed handling of large files that have numerous scattered small changes.
--horizon-lines=lines
Do not discard the last lines lines of the common prefix and the first lines lines of the common suffix.
-i Ignore changes in case; consider upper- and lower-case letters equivalent.
-I regexp
Ignore changes that just insert or delete lines that match regexp.
--ifdef=name
Make merged if-then-else format output, conditional on the preprocessor macro name.
--ignore-all-space
Ignore white space when comparing lines.
--ignore-blank-lines
Ignore changes that just insert or delete blank lines.
--ignore-case
Ignore changes in case; consider upper- and lower-case to be the same.
--ignore-matching-lines=regexp
Ignore changes that just insert or delete lines that match regexp.
--ignore-space-change
Ignore changes in amount of white space.
--initial-tab
Output a tab rather than a space before the text of a line in normal or context format. This causes the
alignment of tabs in the line to look normal.
-l Pass the output through pr to paginate it.
-L label
--label=label
Use label instead of the file name in the context format and unified format headers.
--left-column
Print only the left column of two common lines in side by side format.
--line-format=format
Use format to output all input lines in in-then-else format.
--minimal
Change the algorithm to perhaps find a smaller set of changes. This makes diff slower (sometimes much
slower).
-n Output RCS-format diffs; like -f except that each command specifies the number of lines affected.
-N --new-file In directory comparison, if a file is found in only one directory, treat it as present but empty in the other directory.
--new-group-format=format
Use format to output a group of lines taken from just the second file in if-then-else format.
--new-line-format=format
Use format to output a line taken from just the second file in if-then-else format.
--old-group-format=format
Use format to output a group of lines taken from just the first file in if-then-else format.
--old-line-format=format
Use format to output a line taken from just the first file in if-then-else format.
-p Show which C function each change is in.
-P When comparing directories, if a file appears only in the second directory of the two, treat it as present
but empty in the other.
--paginate
Pass the output through pr to paginate it.
-q Report only whether the files differ, not the details of the differences.
-r When comparing directories, recursively compare any subdirectories found.
--rcs Output RCS-format diffs; like -f except that each command specifies the number of lines affected.
--recursive
When comparing directories, recursively compare any subdirectories found.
--report-identical-files
-s Report when two files are the same.
-S file
When comparing directories, start with the file file. This is used for resuming an aborted comparison.
--from-file=file
Compare file to all operands. file can be a directory.
--to-file=file
Compare all operands to file. file can be a directory.
--sdiff-merge-assist
Print extra information to help sdiff. sdiff uses this option when it runs diff. This option is not
intended for users to use directly.
--show-c-function
Show which C function each change is in.
--show-function-line=regexp
In context and unified format, for each hunk of differences, show some of the last preceding line that
matches regexp.
--side-by-side
Use the side by side output format.
--speed-large-files
Use heuristics to speed handling of large files that have numerous scattered small changes.
--starting-file=file
When comparing directories, start with the file file. This is used for resuming an aborted comparison.
--suppress-common-lines
Do not print common lines in side by side format.
-t Expand tabs to spaces in the output, to preserve the alignment of tabs in the input files.
-T Output a tab rather than a space before the text of a line in normal or context format. This causes the
alignment of tabs in the line to look normal.
--text Treat all files as text and compare them line-by-line, even if they do not appear to be text.
-u Use the unified output format.
--unchanged-group-format=format
Use format to output a group of common lines taken from both files in if-then-else format.
--unchanged-line-format=format
--suppress-common-lines
Do not print common lines in side by side format.
-t Expand tabs to spaces in the output, to preserve the alignment of tabs in the input files.
-T Output a tab rather than a space before the text of a line in normal or context format. This causes the
alignment of tabs in the line to look normal.
--text Treat all files as text and compare them line-by-line, even if they do not appear to be text.
-u Use the unified output format.
--unchanged-group-format=format
Use format to output a group of common lines taken from both files in if-then-else format.
--unchanged-line-format=format
Use format to output a line common to both files in if-then-else format.
--unidirectional-new-file
When comparing directories, if a file appears only in the second directory of the two, treat it as present
but empty in the other.
-U lines
--unified[=lines]
Use the unified output format, showing lines (an integer) lines of context, or three if lines is not
given. For proper operation, patch typically needs at least two lines of context.
-v
--version
Output the version number of diff.
-w Ignore white space when comparing lines.
-W columns
--width=columns
Use an output width of columns in side by side format.
-x pattern
When comparing directories, ignore files and subdirectories whose basenames match pattern.
-X file
When comparing directories, ignore files and subdirectories whose basenames match any pattern contained in
file.
-y Use the side by side output format.
SEE ALSO
cmp(1), comm(1), diff3(1), ed(1), patch(1), pr(1), sdiff(1).
DIAGNOSTICS
An exit status of 0 means no differences were found, 1 means some differences were found, and 2 means trouble.
Sysfs is a virtual file system provided by Linux 2.6. Sysfs exports information about devices and drivers from the kernel device model to userspace, and is also used for configuration. It's similar to sysctl mechanism found in BSD systems, but implemented as a file system instead of a separate mechanism.
Sysfs is designed to export the information present in the device tree which would then no longer clutter up procfs.
Sysfs and userspace
Sysfs is used by several utilities to access information about hardware and its driver (kernel modules) such as udev or HAL. Scripts have been written to access information previously obtained via procfs, and some scripts configure device drivers and devices via their attributes.
2.6 kernel 부터 지원되는 녀석으로, proc filesystem에 지원되지 않는 것들을 지원하기 위한 것이다.
mount 하기 위해서는(되어있지 않았다면)
$ mount -t sysfs sysfs /sys
를 실행해주면 /sys에 마운트 된다.
그리고 sysfs의 정보를 읽기 위해서는 udevinfo를 이용하여 쿼리를 날려주면 된다.
$ ifconfig <interface> [hw <HW> <address>]
<HW>=Hardware Type.
List of possible hardware types:
loop (Local Loopback) slip (Serial Line IP) cslip (VJ Serial Line IP)
slip6 (6-bit Serial Line IP) cslip6 (VJ 6-bit Serial Line IP) adaptive (Adaptive Serial Line IP)
strip (Metricom Starmode IP) ash (Ash) ether (Ethernet)
tr (16/4 Mbps Token Ring) tr (16/4 Mbps Token Ring (New)) ax25 (AMPR AX.25)
netrom (AMPR NET/ROM) rose (AMPR ROSE) tunnel (IPIP Tunnel)
ppp (Point-to-Point Protocol) hdlc ((Cisco)-HDLC) lapb (LAPB)
arcnet (ARCnet) dlci (Frame Relay DLCI) frad (Frame Relay Access Device)
sit (IPv6-in-IPv4) fddi (Fiber Distributed Data Interface) hippi (HIPPI)
irda (IrLAP) ec (Econet) x25 (generic X.25)
eui64 (Generic EUI-64)
※ MAC을 변경하기 위해서는 nic device가 down 되어 있어야 하며, root권한이어야 함.
$ ifconfig eth0 hw ether 00:00:00:00:00:00
SIOCSIFHWADDR: Operation not permitted
$ sudo ifconfig eth0 hw ether 00:00:00:00:00:00
[sudo] password for user:
SIOCSIFHWADDR: Device or resource busy - you may need to down the interface
