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| Argument | Sample output | Explanation |
| %e | 8 | Day of month (leading zero blanked) |
| %h | Mar | Abbreviated month name* |
| %H | 14 | 24-hour-clock hour (two digits) |
| %I | 02 | 12-hour-clock hour (two digits) |
| %j | 067 | Julian day number (three digits) |
| %k | 2 | 12-hour-clock hour (leading zero blanked) |
| %l | 14 | 24-hour-clock hour (leading zero blanked) |
| %m | 03 | Month number (two digits) |
| %M | 54 | Minute (two digits) |
| %n | nn | Newline character |
| %p | PM | AM/PM designation |
| %r | 02:54:40 PM | Hour:minute:second AM/PM designation |
| %R | 14:54 | Hour:minute |
| %S | 40 | Second (two digits) |
| %t | nt | Tab character |
| %T | 14:54:40 | Hour:minute:second |
| %U | 10 | Sunday-based week number (two digits) |
| %w | 3 | Day number (one digit, Sunday is 0) |
| %W | 10 | Monday-based week number (two digits) |
| %x | 03/08/89 | Date* |
| %X | 14:54:40 | Time* |
| %y | 89 | Last two digits of year |
| %Y | 1989 | Year in full |
| %Z | EST | Time zone abbreviation |
| %+ | Wed Mar 8 14:54:40 EST 1989 | Default output format* |
* The exact output depends on the locale.
If a character other than one of those shown in the preceding table appears after a percent sign in the format, that following character is output. All other characters in the format are copied unchanged to the output; a newline character is always added at the end of the output.
In Sunday-based week numbering, the first Sunday of the year begins week 1; days preceding it are part of week 0. In Monday-based week numbering, the first Monday of the year begins week 1.
To set the date, use a command-line argument with one of the following forms:
| 1454 | 24-hour-clock hours (first two digits) and minutes |
| 081454 | Month day (first two digits), hours, and minutes |
| 03081454 | Month (two digits, January is 01), month day, hours, minutes |
| 8903081454 | Year, month, month day, hours, minutes |
| 0308145489 | Month, month day, hours, minutes, year (on System V-compatible systems) |
| 030814541989 | Month, month day, hours, minutes, four-digit year |
| 198903081454 | Four-digit year, month, month day, hours, minutes |
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If the century, year, month, or month day is not given, the current value is used. Any of the preceding forms may be followed by a period and two digits that give the seconds part of the new time; if no seconds are given, zero is assumed.
These options are available:
| _u or _c | Use GMT when setting and showing the date and time. |
| _n | Do not notify other networked systems of the time change. |
| _d dsttype | Set the kernel-stored Daylight Saving Time type to the given value. (The kernel-stored DST type is used mostly by "old" binaries.) |
| _t minutes-west | Set the kernel-stored "minutes west of GMT" value to the one given on the command line. (The kernel-stored DST type is used mostly by "old" binaries.) |
| _a adjustment | Change the time forward (or backward) by the number of seconds (and fractions thereof) specified in the adjustment argument. Either the seconds part or the fractions part of the argument (but not both) may be omitted. On BSD-based systems, the adjustment is made by changing the rate at which time advances; on System-V_based systems, the adjustment is made by changing the time. |
FILES
| /usr/lib/locale/L/LC TIME | Description of time locale L |
| /usr/local/etc/zoneinfo | Time zone information directory |
| /usr/local/etc/zoneinfo/localtime | Local time zone file |
| /usr/local/etc/zoneinfo/posixrules | Used with POSIX-style TZs |
| /usr/local/etc/zoneinfo/GMT | For UTC leap seconds |
If /usr/local/etc/zoneinfo/GMT is absent, UTC leap seconds are loaded from /usr/local/etc/zoneinfo/posixrules.
dd—Convert a file while copying it (data dumper)
SYNOPSIS
dd [—help] [—version] [if=file] [of=file] [ibs=bytes] [obs=bytes] [bs=bytes]
[cbs=bytes] [skip=blocks] [seek=blocks] [count=blocks] [conv={ascii,
ebcdic, ibm, block, unblock, lcase, ucase, swab, noerror, notrunc, sync}]
DESCRIPTION
This manual page documents the GNU version of dd. dd copies a file (from the standard input to the standard output, by default) with a user-selectable blocksize, while optionally performing conversions on it.
OPTIONS
Numbers can be followed by a multiplier:
b=512, c=1, k=1024, w=2, xm=number m
These options are available:
| —help | Print a usage message on standard output and exit successfully. |
| —version | Print version information on standard output then exit successfully. |
| if=file | Read from file instead of the standard input. |
| of=file | Write to file instead of the standard output. Unless conv=notrunc is given, truncate file to the size specified by seek= (0 bytes if seek= is not given). |
| ibs=bytes | Read bytes bytes at a time. |
| obs=bytes | Write bytes bytes at a time. |
| bs=bytes | Read and write bytes bytes at a time. Override ibs and obs. |