FEX(1)FEX(1)NAMEfex - simple and powerful field extraction
SYNOPSISfex selector ...
DESCRIPTIONfex helps you split things by field. Common tasks you might do with awk
or cut are much simpler in fex, and there are things in fex you can't
do nearly as easily in awk or cut.
SELECTOR SYNTAX
The selector syntax looks like this:
<delimiter><selection>...
The delimiter is a single character that is used to split the input
string.
The first delimiter is implied as space ' '. You can specify multiple
fields with curly braces and numbers split by commas. Also valid in
curly braces {} are number ranges. Number ranges are similar to python
array slices, split by colon.
The selection is one of the following and is used to choose fields
split by the delimiter.
a single number
A single number will select that numbered field. Like awk, field
start at 1.
Example selecting third field:
% echo "a b c d e" | fex '3'
a b c d
Example selecting the second field delimited by slash:
% echo "/home/hello/world" | fex '/2'
hello
{N:M}
This is a range selection. The syntax for ranges is, in curly
braces, N:M, which chooses the fields in range N to M, inclusive.
Example selecting first through fourth fields:
% echo "a b c d e" | fex '{1:4}'
a b c d
{N,M,...}
The syntax for multiple selections is numbers within curly braces.
Example selecting first and fifth fields:
% echo "a b c d e" | fex '{1,5}'
a e
{range,field,field,range,field}
Combining the above, you can actually select ranges and individual
fields using the {...} syntax by delimiting each selection by
comma.
Example selecting fields 1 to 3, and 5: {1:3,5}
% echo "a b c d e" | fex '{1:3,5}'
a b c e
{?range,field,...}
The {?...} notation turns on 'non greedy' field separation. The
differences here can be shown best by example, first:
% echo "1...2.3.4" | fex '.{1:3}'
1.2.3
% echo "1...2.3.4" | fex '.{?1:3}'
1..
In the first example, fex uses '.' as delimiter and ignores empty
fields. In the second example (non greedy), it does not ignore
those empty fields.
/regexp/
The /regexp/ selection will choose only fields that match the given
pattern.
Example, pulling out words with 'addr:' in it from 'ifconfig'
output:
% ifconfig | fex ' /addr:[0-9]/'
addr:127.0.0.1
addr:192.168.0.28
EXAMPLES
Show the MTU for a given interface
The 'mtu' in ifconfig output looks like 'mtu:1500'. So have fex
split by space, then grab fields matching /mtu:/, split by colon,
and choose the last field.
% ifconfig wlan0 | fex ' /mtu:/:-1'
1500
Parse apache logs
Pull the IP address (first field by space) and the path requested
(2nd field in "GET <path> ...")
% fex 1 '"2 2' < /b/logs/access
65.57.245.11 /
65.57.245.11 /icons/blank.gif
65.57.245.11 /icons/folder.gif
SEE ALSOawk(1), cut(1),
Project site: <http://www.semicomplete.com/projects/fex>
Source Code: <https://github.com/jordansissel/fex>
CONTACT
Please send questions to jls@semicomplete.com
File bugs and feature requests at the following URL:
<https://github.com/jordansissel/fex/issues>
Alternately, if you prefer email, feel free to file bugs by email.
Whatever works for you :)
Patches, ideas, and other contributions by many, nice folks. See the
CHANGELIST file for who provided what.
AUTHORfex was written by Jordan Sissel.
2012-03-13 FEX(1)
