README

December 13, 2024 · View on GitHub

ARR(1) General Commands Manual ARR(1)

NAME arr – (re)arrange and select fields on each line

SYNOPSIS arr [-0] [-P | -p padding] expr [files ...]

DESCRIPTION arr unifies and extends the features of cut(1), paste(1), and provides an alternative to dicer(5).

 arr will read one line (or zero separated string, when -0 is used) from
 each file passed on the command line, and then print the result of
 expanding expr.

 By default, reading continues until all files are exhausted.  Ended files
 continue generating empty strings, or padding when -p is used.  When -P
 is used, reading stops as soon as one file is exhausted.

FORMATTING EXPRESSIONS expr is read as a string containing escape sequences ‘%{...}’ which are parsed according to the following EBNF:

       <expr>   ::= <fields> (("|" <char> | "*") <fields>)* ("&" <char>)?
       <fields> ::= "~"? <field> ("," <field>)*
       <field>  ::= "-"? ""+ | ("-"? ""+)? ":" ("-"? ""+)?

 Fields are specified by their position, negative numbers count from the
 end.  Field ranges are written like n:m where n and m are optional and
 default to 1 and -1 respectively.  If n is bigger than m, fields are
 expanded in reverse order.

 Field ranges are combined using , and an initial ~ negates the whole set
 of field selections.

 Selected fields are joined with the last separator, and then split on c
 when |c is used.  Alternatively, * splits byte-wise.  A final &c joins
 the selected fields using c again.

 The first set of fields corresponds to the lines read from each file.

EXIT STATUS The arr utility exits 0 on success, and >0 if an error occurs.

EXAMPLES Print all users from /etc/passwd (read: ‘take line from file 1, split on :, print field 1.’):

       arr '%{1|:1}' /etc/passwd

 List all basenames of shells used (read ‘take line from file 1, split on
 :, take last field, split on /, take last field.’):

       arr '%{1|:-1|/-1}' /etc/passwd | sort -u

 Remove the TLD from a list of domains:

       arr '%{1|.~-1}'

 Generate PTR addresses for a list of IPv4s:

       arr '%{1|.-1:1}.in-addr.arpa'

 Only print the first 80 chars of each line:

       arr '%{1*:80}'

 Double space text:

       arr '%{1*:& }'

 Format a phone number:

       echo 8005551212 | arr '(%{1*1:3})%{1*4:6}-%{1*7:}'