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26.2 numfmt: Reformat numbers

numfmt reads numbers in various representations and reformats them as requested. The most common usage is converting numbers to/from human representation (e.g. ‘4G’ → ‘4,000,000,000’).

numfmt [option]… [number]

numfmt converts each number on the command-line according to the specified options (see below). If no numbers are given, it reads numbers from standard input. numfmt can optionally extract numbers from specific columns, maintaining proper line padding and alignment.

An exit status of zero indicates success, and a nonzero value indicates failure.

See --invalid for additional information regarding exit status.

26.2.1 General options

The program accepts the following options. Also see Common options.

--debug

Print (to standard error) warning messages about possible erroneous usage.

-d d
--delimiter=d

Use the character d as input field separator (default: whitespace). Note: Using non-default delimiter turns off automatic padding.

--field=fields

Convert the number in input field fields (default: 1). fields supports cut style field ranges:

N    N'th field, counted from 1
N-   from N'th field, to end of line
N-M  from N'th to M'th field (inclusive)
-M   from first to M'th field (inclusive)
-    all fields
--format=format

Use printf-style floating FORMAT string. The format string must contain one ‘%f’ directive, optionally with ‘'’, ‘-’, ‘0’, width or precision modifiers. The ‘'’ modifier will enable --grouping, the ‘-’ modifier will enable left-aligned --padding and the width modifier will enable right-aligned --padding. The ‘0’ width modifier (without the ‘-’ modifier) will generate leading zeros on the number, up to the specified width. A precision specification like ‘%.1f’ will override the precision determined from the input data or set due to --to option auto scaling.

--from=unit

Auto-scales input numbers according to unit. See UNITS below. The default is no scaling, meaning suffixes (e.g. ‘M’, ‘G’) will trigger an error.

--from-unit=n

Specify the input unit size (instead of the default 1). Use this option when the input numbers represent other units (e.g. if the input number ‘10’ represents 10 units of 512 bytes, use ‘--from-unit=512’). Suffixes are handled as with ‘--from=auto’.

--grouping

Group digits in output numbers according to the current locale’s grouping rules (e.g Thousands Separator character, commonly ‘.’ (dot) or ‘,’ comma). This option has no effect in ‘POSIX/C’ locale.

--header[=n]

Print the first n (default: 1) lines without any conversion.

--invalid=mode

The default action on input errors is to exit immediately with status code 2. --invalid=abort explicitly specifies this default mode. With a mode of ‘fail’, print a warning for each conversion error, and exit with status 2. With a mode of ‘warn’, exit with status 0, even in the presence of conversion errors, and with a mode of ‘ignore’ do not even print diagnostics.

--padding=n

Pad the output numbers to n characters, by adding spaces. If n is a positive number, numbers will be right-aligned. If n is a negative number, numbers will be left-aligned. By default, numbers are automatically aligned based on the input line’s width (only with the default delimiter).

--round=method

When converting number representations, round the number according to method, which can be ‘up’, ‘down’, ‘from-zero’ (the default), ‘towards-zero’, ‘nearest’.

--suffix=suffix

Add ‘SUFFIX’ to the output numbers, and accept optional ‘SUFFIX’ in input numbers.

--to=unit

Auto-scales output numbers according to unit. See Units below. The default is no scaling, meaning all the digits of the number are printed.

--to-unit=n

Specify the output unit size (instead of the default 1). Use this option when the output numbers represent other units (e.g. to represent ‘4,000,000’ bytes in blocks of 1KB, use ‘--to=si --to-unit=1000’). Suffixes are handled as with ‘--from=auto’.

-z
--zero-terminated

Delimit items with a zero byte rather than a newline (ASCII LF). I.e., treat input as items separated by ASCII NUL and terminate output items with ASCII NUL. This option can be useful in conjunction with ‘perl -0’ or ‘find -print0’ and ‘xargs -0’ which do the same in order to reliably handle arbitrary file names (even those containing blanks or other special characters). Note with -z the newline character is treated as a field separator.

26.2.2 Possible units:

The following are the possible unit options with --from=UNITS and --to=UNITS:

none

No scaling is performed. For input numbers, no suffixes are accepted, and any trailing characters following the number will trigger an error. For output numbers, all digits of the numbers will be printed.

si

Auto-scale numbers according to the International System of Units (SI) standard. For input numbers, accept one of the following suffixes. For output numbers, values larger than 1000 will be rounded, and printed with one of the following suffixes:

K’  =>  1000^1 = 10^3 (Kilo)
‘M’  =>  1000^2 = 10^6 (Mega)
‘G’  =>  1000^3 = 10^9 (Giga)
‘T’  =>  1000^4 = 10^{12} (Tera)
‘P’  =>  1000^5 = 10^{15} (Peta)
‘E’  =>  1000^6 = 10^{18} (Exa)
‘Z’  =>  1000^7 = 10^{21} (Zetta)
‘Y’  =>  1000^8 = 10^{24} (Yotta)
iec

Auto-scale numbers according to the International Electrotechnical Commission (IEC) standard. For input numbers, accept one of the following suffixes. For output numbers, values larger than 1024 will be rounded, and printed with one of the following suffixes:

K’  =>  1024^1 = 2^{10} (Kibi)
‘M’  =>  1024^2 = 2^{20} (Mebi)
‘G’  =>  1024^3 = 2^{30} (Gibi)
‘T’  =>  1024^4 = 2^{40} (Tebi)
‘P’  =>  1024^5 = 2^{50} (Pebi)
‘E’  =>  1024^6 = 2^{60} (Exbi)
‘Z’  =>  1024^7 = 2^{70} (Zebi)
‘Y’  =>  1024^8 = 2^{80} (Yobi)

The iec option uses a single letter suffix (e.g. ‘G’), which is not fully standard, as the iec standard recommends a two-letter symbol (e.g ‘Gi’) - but in practice, this method common. Compare with the iec-i option.

iec-i

Auto-scale numbers according to the International Electrotechnical Commission (IEC) standard. For input numbers, accept one of the following suffixes. For output numbers, values larger than 1024 will be rounded, and printed with one of the following suffixes:

Ki’  =>  1024^1 = 2^{10} (Kibi)
‘Mi’  =>  1024^2 = 2^{20} (Mebi)
‘Gi’  =>  1024^3 = 2^{30} (Gibi)
‘Ti’  =>  1024^4 = 2^{40} (Tebi)
‘Pi’  =>  1024^5 = 2^{50} (Pebi)
‘Ei’  =>  1024^6 = 2^{60} (Exbi)
‘Zi’  =>  1024^7 = 2^{70} (Zebi)
‘Yi’  =>  1024^8 = 2^{80} (Yobi)

The iec-i option uses a two-letter suffix symbol (e.g. ‘Gi’), as the iec standard recommends, but this is not always common in practice. Compare with the iec option.

auto

auto’ can only be used with --from. With this method, numbers with ‘K’,‘M’,‘G’,‘T’,‘P’,‘E’,‘Z’,‘Y’ suffixes are interpreted as SI values, and numbers with ‘Ki’, ‘Mi’,‘Gi’,‘Ti’,‘Pi’,‘Ei’,‘Zi’,‘Yi’ suffixes are interpreted as IEC values.

26.2.3 Examples of using numfmt

Converting a single number from/to human representation:

$ numfmt --to=si 500000
500K

$ numfmt --to=iec 500000
489K

$ numfmt --to=iec-i 500000
489Ki

$ numfmt --from=si 1M
1000000

$ numfmt --from=iec 1M
1048576

# with '--from=auto', M=Mega, Mi=Mebi
$ numfmt --from=auto 1M
1000000
$ numfmt --from=auto 1Mi
1048576

Converting from ‘SI’ to ‘IEC’ scales (e.g. when a harddisk capacity is advertised as ‘1TB’, while checking the drive’s capacity gives lower values):

$ numfmt --from=si --to=iec 1T
932G

Converting a single field from an input file / piped input (these contrived examples are for demonstration purposes only, as both ls and df support the --human-readable option to output sizes in human-readable format):

# Third field (file size) will be shown in SI representation
$ ls -log | numfmt --field 3 --header --to=si | head -n4
-rw-r--r--  1     94K Aug 23  2011 ABOUT-NLS
-rw-r--r--  1    3.7K Jan  7 16:15 AUTHORS
-rw-r--r--  1     36K Jun  1  2011 COPYING
-rw-r--r--  1       0 Jan  7 15:15 ChangeLog

# Second field (size) will be shown in IEC representation
$ df --block-size=1 | numfmt --field 2 --header --to=iec | head -n4
File system   1B-blocks        Used  Available Use% Mounted on
rootfs             132G   104741408   26554036  80% /
tmpfs              794M        7580     804960   1% /run/shm
/dev/sdb1          694G   651424756   46074696  94% /home

Output can be tweaked using --padding or --format:

# Pad to 10 characters, right-aligned
$ du -s * | numfmt --to=si --padding=10
      2.5K config.log
       108 config.status
      1.7K configure
        20 configure.ac

# Pad to 10 characters, left-aligned
$ du -s * | numfmt --to=si --padding=-10
2.5K       config.log
108        config.status
1.7K       configure
20         configure.ac

# Pad to 10 characters, left-aligned, using 'format'
$ du -s * | numfmt --to=si --format="%10f"
      2.5K config.log
       108 config.status
      1.7K configure
        20 configure.ac

# Pad to 10 characters, left-aligned, using 'format'
$ du -s * | numfmt --to=si --padding="%-10f"
2.5K       config.log
108        config.status
1.7K       configure
20         configure.ac

With locales that support grouping digits, using --grouping or --format enables grouping. In ‘POSIX’ locale, grouping is silently ignored:

$ LC_ALL=C numfmt --from=iec --grouping 2G
2147483648

$ LC_ALL=en_US.utf8 numfmt --from=iec --grouping 2G
2,147,483,648

$ LC_ALL=ta_IN numfmt --from=iec --grouping 2G
2,14,74,83,648

$ LC_ALL=C ./src/numfmt --from=iec --format="==%'15f==" 2G
==     2147483648==

$ LC_ALL=en_US.utf8 ./src/numfmt --from=iec --format="==%'15f==" 2G
==  2,147,483,648==

$ LC_ALL=en_US.utf8 ./src/numfmt --from=iec --format="==%'-15f==" 2G
==2,147,483,648  ==

$ LC_ALL=ta_IN ./src/numfmt --from=iec --format="==%'15f==" 2G
== 2,14,74,83,648==

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