1FEX(1) FEX(1)
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6 fex - simple and powerful field extraction
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9 fex selector ...
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12 fex helps you split things by field. Common tasks you might do with awk
13 or cut are much simpler in fex, and there are things in fex you can't
14 do nearly as easily in awk or cut.
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17 The selector syntax looks like this:
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19 <delimiter><selection>...
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21 The delimiter is a single character that is used to split the input
22 string.
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24 The first delimiter is implied as space ' '. You can specify multiple
25 fields with curly braces and numbers split by commas. Also valid in
26 curly braces {} are number ranges. Number ranges are similar to python
27 array slices, split by colon.
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29 The selection is one of the following and is used to choose fields
30 split by the delimiter.
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32 a single number
33 A single number will select that numbered field. Like awk, field
34 start at 1.
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36 Example selecting third field:
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38 % echo "a b c d e" | fex '3'
39 a b c d
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41 Example selecting the second field delimited by slash:
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43 % echo "/home/hello/world" | fex '/2'
44 hello
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46 {N:M}
47 This is a range selection. The syntax for ranges is, in curly
48 braces, N:M, which chooses the fields in range N to M, inclusive.
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50 Example selecting first through fourth fields:
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52 % echo "a b c d e" | fex '{1:4}'
53 a b c d
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55 {N,M,...}
56 The syntax for multiple selections is numbers within curly braces.
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58 Example selecting first and fifth fields:
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60 % echo "a b c d e" | fex '{1,5}'
61 a e
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63 {range,field,field,range,field}
64 Combining the above, you can actually select ranges and individual
65 fields using the {...} syntax by delimiting each selection by
66 comma.
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68 Example selecting fields 1 to 3, and 5: {1:3,5}
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70 % echo "a b c d e" | fex '{1:3,5}'
71 a b c e
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73 {?range,field,...}
74 The {?...} notation turns on 'non greedy' field separation. The
75 differences here can be shown best by example, first:
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77 % echo "1...2.3.4" | fex '.{1:3}'
78 1.2.3
79 % echo "1...2.3.4" | fex '.{?1:3}'
80 1..
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82 In the first example, fex uses '.' as delimiter and ignores empty
83 fields. In the second example (non greedy), it does not ignore
84 those empty fields.
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86 /regexp/
87 The /regexp/ selection will choose only fields that match the given
88 pattern.
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90 Example, pulling out words with 'addr:' in it from 'ifconfig'
91 output:
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93 % ifconfig | fex ' /addr:[0-9]/'
94 addr:127.0.0.1
95 addr:192.168.0.28
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98 Show the MTU for a given interface
99 The 'mtu' in ifconfig output looks like 'mtu:1500'. So have fex
100 split by space, then grab fields matching /mtu:/, split by colon,
101 and choose the last field.
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103 % ifconfig wlan0 | fex ' /mtu:/:-1'
104 1500
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106 Parse apache logs
107 Pull the IP address (first field by space) and the path requested
108 (2nd field in "GET <path> ...")
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110 % fex 1 '"2 2' < /b/logs/access
111 65.57.245.11 /
112 65.57.245.11 /icons/blank.gif
113 65.57.245.11 /icons/folder.gif
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116 awk(1), cut(1),
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118 Project site: <http://www.semicomplete.com/projects/fex>
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120 Source Code: <https://github.com/jordansissel/fex>
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123 Please send questions to jls@semicomplete.com
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125 File bugs and feature requests at the following URL:
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127 <https://github.com/jordansissel/fex/issues>
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129 Alternately, if you prefer email, feel free to file bugs by email.
130 Whatever works for you :)
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132 Patches, ideas, and other contributions by many, nice folks. See the
133 CHANGELIST file for who provided what.
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136 fex was written by Jordan Sissel.
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140 2022-07-21 FEX(1)