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+ readme: add an initial readme for the project
right now it's just copied literally from the usage header at the top of the script. we should put a makefile and generate this. later...
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| field | ||
| ============================================================================== | ||
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| :: | ||
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| field [options] [args] | ||
| select and output fields from each record of stdin | ||
| args: | ||
| - 1-arg: field [options] <rangelist> | ||
| - 2-arg: field [non-field opts] <indelim> <rangelist> | ||
| - 3-arg: field [non-field opts] <indelim> <outdelim> <rangelist> | ||
| - if -r/--regex, indelim is a python regular expression | ||
| - field and record delimiters can also be given as options | ||
| - fixed delimiters are python string literals | ||
| - regex delimiters are python raw strings | ||
| fields: | ||
| - defaults to whitespace: 'bytes.split(sep=None)' | ||
| - if supplied as $1, uses 'bytes.split(sep="$1")' | ||
| - if '-r', uses 're.split(r'$1')' | ||
| - if '-i <value>', uses 'bytes.split(sep="<value>")' | ||
| - if '-F <value>', uses 're.split(r"<value>")' | ||
| - if $IFS set, splits on its chars: 're.split(f"[{getenv(IFS)}]+")' | ||
| - if '-e', all empty fields are discarded | ||
| - if '-G', only leading or trailing blank fields are discarded | ||
| records: | ||
| - defaults to newline: 'bytes.split(sep="\n")' | ||
| - if '-I <value>', uses 'bytes.split(sep="<value>")' | ||
| - if '-R <value>', uses 're.split(r"<value>")' | ||
| - if '-E', empty records in input are discarded | ||
| - if '-N', trailing separator on last record not emitted | ||
| - processes input as bytes, in chunks of io.DEFAULT_BUFFER_SIZE | ||
| - chunk size overridden with '-b/--bsz' (optional k or m suffix) | ||
| outdelims: | ||
| - fields default to space, ie '\x20', or via $2, or via -o/--ofs | ||
| - records default to newline, ie '\n', or via -O/--ors | ||
| rangelist: | ||
| - specifier is a comma separated list of ranges | ||
| - ranges are either single numbers or first-last sequences | ||
| - unspecified Y in X-Y will default to highest Y in the input | ||
| - if first field in range greater than than last, print reversed | ||
| - if any specified fields do not exist in the record, skip them | ||
| - field '0' is the same as all fields (range '1-') | ||
| range: | ||
| N: just field number N (1 is first) | ||
| -N: just field Nth from the end (-1 is last) | ||
| N-M: fields N through M (M > N) | ||
| N-M: fields M through N, backwards (N > M) | ||
| N-: fields N through the end | ||
| -N-: fields from Nth from the end, through the end | ||
| N--M: fields N through Mth from end | ||
| -N--M: fields Nth from the end through Mth from the end | ||
| examples: | ||
| "echo one two three four five | field 2 -> "two" | ||
| "echo one two three four five | field -2" -> "four" | ||
| "echo one two three four five | field 2-4" -> "two three four" | ||
| "echo one two three four five | field 4-2" -> "four three two" | ||
| "echo one two three four five | field 3-" -> "three four five" | ||
| "echo one two three four five | field -2-" -> "four five" | ||
| "echo one two three | field 1,0" -> "one one two three" | ||
| "echo {1..12} | field -8--10" -> "5 4 3" | ||
| "echo {1..12} | field -8--15" -> "5 4 3 2 1" | ||
| "echo {1..12} | field 3--15" -> "3 2 1" | ||
| "echo {1..12} | field 1-3,-1--2,8,8,10-,-2" -> "1 2 3 12 11 8 8 10 11 12 11" | ||
| todo: | ||
| - read from files given as additional arguments | ||
| - /R/-/S/: starting with /R/ and ending with /S/ | ||
| - specify record selection criteria (pattern) | ||
| - field reformatting, eg wrapping, fit in column or on page | ||
| - args like -g columnate_group | ||
| - different behaviors for range overlaps (set union, addition) | ||
| - way to disinclude fields ("all fields except...") | ||
| - multiple delimiters, maybe a -i and -d possible for every -f | ||
| - multiple delimiters, as in multiple patterns will serve as one | ||
| - implement a "record" in terms of "field?" | ||
| - flag to discard empty records in output (no non-empty fields) | ||
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| ____ | ||
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| | [email protected] | ||
| | https://github.com/smemsh/field | ||
| | https://spdx.org/licenses/GPL-2.0 |