Online help - Miller

<div> Quick links:   <a class="quicklink" href="../reference-main-flag-list/index.html">Flags</a>   <a class="quicklink" href="../reference-verbs/index.html">Verbs</a>   <a class="quicklink" href="../reference-dsl-builtin-functions/index.html">Functions</a>   <a class="quicklink" href="../glossary/index.html">Glossary</a>   <a class="quicklink" href="../release-docs/index.html">Release docs</a> </div> # Online help

Miller has several online help mechanisms built in.

Main help

The front door is mlr --help or its synonym mlr -h. This leads you to mlr help topics with its list of specific areas:

<pre class="pre-highlight-in-pair"> mlr --help </pre> <pre class="pre-non-highlight-in-pair"> Usage: mlr [flags] {verb} [verb-dependent options ...] {zero or more file names} If zero file names are provided, standard input is read, e.g. mlr --csv sort -f shape example.csv Output of one verb may be chained as input to another using "then", e.g. mlr --csv stats1 -a min,mean,max -f quantity then sort -f color example.csv Please see 'mlr help topics' for more information. Please also see https://miller.readthedocs.io </pre> <pre class="pre-highlight-in-pair"> mlr help topics </pre> <pre class="pre-non-highlight-in-pair"> Type 'mlr help {topic}' for any of the following: Essentials: mlr help topics mlr help basic-examples mlr help file-formats Flags: mlr help flags mlr help flag mlr help list-separator-aliases mlr help list-separator-regex-aliases mlr help comments-in-data-flags mlr help compressed-data-flags mlr help csv/tsv-only-flags mlr help dkvp-only-flags mlr help file-format-flags mlr help flatten-unflatten-flags mlr help format-conversion-keystroke-saver-flags mlr help json-only-flags mlr help legacy-flags mlr help miscellaneous-flags mlr help output-colorization-flags mlr help pprint-only-flags mlr help profiling-flags mlr help separator-flags Verbs: mlr help list-verbs mlr help usage-verbs mlr help verb Functions: mlr help list-functions mlr help list-function-classes mlr help list-functions-in-class mlr help usage-functions mlr help usage-functions-by-class mlr help function Keywords: mlr help list-keywords mlr help usage-keywords mlr help keyword Other: mlr help auxents mlr help terminals mlr help mlrrc mlr help output-colorization mlr help type-arithmetic-info mlr help type-arithmetic-info-extended Shorthands: mlr -g = mlr help flags mlr -l = mlr help list-verbs mlr -L = mlr help usage-verbs mlr -f = mlr help list-functions mlr -F = mlr help usage-functions mlr -k = mlr help list-keywords mlr -K = mlr help usage-keywords Lastly, 'mlr help ...' will search for your exact text '...' using the sources of 'mlr help flag', 'mlr help verb', 'mlr help function', and 'mlr help keyword'. Use 'mlr help find ...' for approximate (substring) matches, e.g. 'mlr help find map' for all things with "map" in their names. </pre>

If you know the name of the thing you're looking for, use mlr help:

<pre class="pre-highlight-in-pair"> mlr help map </pre> <pre class="pre-non-highlight-in-pair"> map: declares a map-valued local variable in the current curly-braced scope. Type-checking happens at assignment: 'map b = 0' is an error. map b = {} is always OK. map b = a is OK or not depending on whether a is a map. </pre>

To search by substring, use mlr help find:

<pre class="pre-highlight-in-pair"> mlr help find gmt </pre> <pre class="pre-non-highlight-in-pair"> sec2gmtdate Usage: ../c/mlr sec2gmtdate {comma-separated list of field names} Replaces a numeric field representing seconds since the epoch with the corresponding GMT year-month-day timestamp; leaves non-numbers as-is. This is nothing more than a keystroke-saver for the sec2gmtdate function: ../c/mlr sec2gmtdate time1,time2 is the same as ../c/mlr put '$time1=sec2gmtdate($time1);$time2=sec2gmtdate($time2)' sec2gmt Usage: mlr sec2gmt [options] {comma-separated list of field names} Replaces a numeric field representing seconds since the epoch with the corresponding GMT timestamp; leaves non-numbers as-is. This is nothing more than a keystroke-saver for the sec2gmt function: mlr sec2gmt time1,time2 is the same as mlr put '$time1 = sec2gmt($time1); $time2 = sec2gmt($time2)' Options: -1 through -9: format the seconds using 1..9 decimal places, respectively. --millis Input numbers are treated as milliseconds since the epoch. --micros Input numbers are treated as microseconds since the epoch. --nanos Input numbers are treated as nanoseconds since the epoch. -h|--help Show this message. gmt2localtime (class=time #args=1,2) Convert from a GMT-time string to a local-time string. Consulting $TZ unless second argument is supplied. Examples: gmt2localtime("1999-12-31T22:00:00Z") = "2000-01-01 00:00:00" with TZ="Asia/Istanbul" gmt2localtime("1999-12-31T22:00:00Z", "Asia/Istanbul") = "2000-01-01 00:00:00" gmt2nsec (class=time #args=1) Parses GMT timestamp as integer nanoseconds since the epoch. Example: gmt2nsec("2001-02-03T04:05:06Z") = 981173106000000000 gmt2sec (class=time #args=1) Parses GMT timestamp as integer seconds since the epoch. Example: gmt2sec("2001-02-03T04:05:06Z") = 981173106 localtime2gmt (class=time #args=1,2) Convert from a local-time string to a GMT-time string. Consults $TZ unless second argument is supplied. Examples: localtime2gmt("2000-01-01 00:00:00") = "1999-12-31T22:00:00Z" with TZ="Asia/Istanbul" localtime2gmt("2000-01-01 00:00:00", "Asia/Istanbul") = "1999-12-31T22:00:00Z" nsec2gmt (class=time #args=1,2) Formats integer nanoseconds since epoch as GMT timestamp. Leaves non-numbers as-is. With second integer argument n, includes n decimal places for the seconds part. Examples: nsec2gmt(1234567890000000000) = "2009-02-13T23:31:30Z" nsec2gmt(1234567890123456789) = "2009-02-13T23:31:30Z" nsec2gmt(1234567890123456789, 6) = "2009-02-13T23:31:30.123456Z" nsec2gmtdate (class=time #args=1) Formats integer nanoseconds since epoch as GMT timestamp with year-month-date. Leaves non-numbers as-is. Example: sec2gmtdate(1440768801700000000) = "2015-08-28". sec2gmt (class=time #args=1,2) Formats seconds since epoch as GMT timestamp. Leaves non-numbers as-is. With second integer argument n, includes n decimal places for the seconds part. Examples: sec2gmt(1234567890) = "2009-02-13T23:31:30Z" sec2gmt(1234567890.123456) = "2009-02-13T23:31:30Z" sec2gmt(1234567890.123456, 6) = "2009-02-13T23:31:30.123456Z" sec2gmtdate (class=time #args=1) Formats seconds since epoch (integer part) as GMT timestamp with year-month-date. Leaves non-numbers as-is. Example: sec2gmtdate(1440768801.7) = "2015-08-28". </pre>

Etc.

Command-line flags

This is a command-line version of the List of command-line flags page. See mlr help flags for a full listing.

Per-verb help

This is a command-line version of the List of verbs page. Given the name of a verb (from mlr -l) you can invoke it with --help or -h -- or, use mlr help verb:

<pre class="pre-highlight-in-pair"> mlr cat --help </pre> <pre class="pre-non-highlight-in-pair"> Usage: mlr cat [options] Passes input records directly to output. Most useful for format conversion. Options: -n Prepend field "n" to each record with record-counter starting at 1. -N {name} Prepend field {name} to each record with record-counter starting at 1. -g {a,b,c} Optional group-by-field names for counters, e.g. a,b,c --filename Prepend current filename to each record. --filenum Prepend current filenum (1-up) to each record. -h|--help Show this message. </pre> <pre class="pre-highlight-in-pair"> mlr group-like -h </pre> <pre class="pre-non-highlight-in-pair"> Usage: mlr group-like [options] Outputs records in batches having identical field names. Options: -h|--help Show this message. </pre> <pre class="pre-highlight-in-pair"> mlr help verb sort </pre> <pre class="pre-non-highlight-in-pair"> sort Usage: mlr sort {flags} Sorts records primarily by the first specified field, secondarily by the second field, and so on. (Any records not having all specified sort keys will appear at the end of the output, in the order they were encountered, regardless of the specified sort order.) The sort is stable: records that compare equal will sort in the order they were encountered in the input record stream. Options: -f {comma-separated field names} Lexical ascending -r {comma-separated field names} Lexical descending -c {comma-separated field names} Case-folded lexical ascending -cr {comma-separated field names} Case-folded lexical descending -n {comma-separated field names} Numerical ascending; nulls sort last -nf {comma-separated field names} Same as -n -nr {comma-separated field names} Numerical descending; nulls sort first -t {comma-separated field names} Natural ascending -b Move sort fields to start of record, as in reorder -b -tr|-rt {comma-separated field names} Natural descending -h|--help Show this message. Example: mlr sort -f a,b -nr x,y,z which is the same as: mlr sort -f a -f b -nr x -nr y -nr z </pre>

Etc.

Per-function help

This is a command-line version of the DSL built-in functions page. Given the name of a DSL function (from mlr -f) you can use mlr help function for details:

<pre class="pre-highlight-in-pair"> mlr help function append </pre> <pre class="pre-non-highlight-in-pair"> append (class=collections #args=2) Appends second argument to end of first argument, which must be an array. </pre> <pre class="pre-highlight-in-pair"> mlr help function split </pre> <pre class="pre-non-highlight-in-pair"> Function "split" not found. </pre> <pre class="pre-highlight-in-pair"> mlr help function splita </pre> <pre class="pre-non-highlight-in-pair"> splita (class=conversion #args=2) Splits string into array with type inference. First argument is string to split; second is the separator to split on. Example: splita("3,4,5", ",") = [3,4,5] </pre>

Etc.

REPL help

You can use :h or :help inside the REPL:

<pre class="pre-highlight-in-pair"> $ mlr repl </pre> <pre class="pre-non-highlight-in-pair"> Miller v6.0.0-dev REPL for darwin:amd64:go1.16.5 Docs: https://miller.readthedocs.io Type ':h' or ':help' for on-line help; ':q' or ':quit' to quit. [mlr] :h Options: :help intro :help examples :help repl-list :help repl-details :help prompt :help function-names :help function-details :help {function name}, e.g. :help sec2gmt :help {function name}, e.g. :help sec2gmt [mlr] </pre>

Manual page

If you've gotten Miller from a package installer, you should have man mlr producing a traditional manual page. If not, no worries -- the manual page is a concatenated listing of the same information also available by each of the topics in mlr help topics. See also the Manual page which is an online copy.