Go line scanner
Glin is similar in concept to "awk" but offers a more limited and simplified interface.
Glin reads lines from standard input, splits each line into fields, and writes a re-ordered list of fields.
A common usage for glin is to "filter" a log file and return only a limited set of fields.
glin [options] [output field list]
Options:
-after string
process fields in line after specified tag (remove text before tag)
-after-line string
process lines after lines that matches
-after-linen int
process lines after n lines
-before string
process fields in line before specified tag (remove text after tag)
-before-line string
process lines before lines that matches
-begin string
expression to be executed before processing lines
-contains string
output only lines that contains the pattern
-debug
print debug info
-end string
expression to be executed after processing lines
-expr string
expression to be executed for each line
-grep string
output only lines that match the regular expression
-ifn int
maximum number of fields when splitting input (<1=all) (default -1)
-ifs string
input field separator (default " ")
-ifs-re string
input field separator (as regular expression)
-line
print line numbers
-matches string
return status code 100 if any line matches the specified pattern, 101 otherwise
-ofs string
output field separator (default " ")
-print-expr
print result of -expr
-printf string
output is formatted according to specified format
-quote
quote returned fields
-re string
regular expression for parsing input
-remove
remove specified fields instead of selecting them
-shlex
split using shlex/shell-style rules
-test string
test expression (skip line if false)
-ucount
print unique lines (and count)
-uniq
print only unique lines
-unquote
quote returned fields
-version
print version and exit
Output field list: one or more indices (or slices) of fields to return. Also, use `{{expr}}` to return the current value of `-expr` or `{{expr:varname}}` to return the value of variable `varname`.
Expressions use the syntax described here with the following additions:
-
It's possible to set variables:
name=exprAnd use variables:
$name -
The following variables are predefined (same as
awk):- $NR : current number of records / lines
- $NF : number of fields in the current line
- $0 : the current line
- $1 to $NF: the value of the numbered field
-
The following functions are available:
- print(args...) : print one or more arguments
- format(fmt, args...) : format one or more arguments according to
fmt(likesprintf) - num("string") : convert
stringto float, to apply numeric operations - int("string") : convert
stringto int, to apply numberic operations - len("string") : return length of
string - substr("string", start, [len]) : return substring of
stringstarting fromstart(truncate tolencharacters if `len is specified)
Also:
- Slices follow the Go slice convention (start:end) or better, the Python slice convention (negative values are offsets from the end, so -1 is the last field).
- Field 0 is the input line (as in "awk") so the various fields are indexed from 1 to the number of fields.