the only way I could make sense of why that works is awk prints out whatever line that are between the two patterns, without much directionality.
Code:
/pattern2/ {on=0} on
when pattern2 is found, store the lines but do not print, is that correct?
No. See below.
Quote:
Code:
/pattern1/ {on=1}
when pattern1 is found turn on print.
Yes.
Quote:
But pattern 1 occurs before pattern 2 in the table. So what is it printing? I think awk works its way down the table as it executes the command, so that code doesn't make much logical sense to me. Or does it not work like that?
Please try diving in deeper into awk by reading man pages or other literature. awk in very general terms does the following: execute the BEGIN action (if exists), then read input line after line, and apply the program steps given sequentially to each line. Program steps consist of pattern {action} pairs, in priciple. Whenever a pattern evaluates to TRUE, execute the action. The default action is {print}. So in your case
Code:
... # read line
/pattern2/ {on=0} # does closing pattern occur in the line --> store THE FACT (implies not printing the closing line)
on # default print if on (on == TRUE), don't if FALSE
/pattern1/ {on=1} # does opening pattern occur in the line --> store THE FACT (implies not having printed the opening line)
...
So, as you can see, by carefully arranging the steps you can tailor the output to your needs.
BTW - you could, of course, append the down-the-line awk processing that you mentioned before into the above awk program...
Hi,
I have an array.
@arr=("abcdefgh","ppppppp","rrr");
$tofind="rrr";#string to find.
I want to match this string and retrieve only matched contents.
In this case rrr is found in 2nd position in an array i want to print only rrr.
If the string is matched i have to retrieve only... (1 Reply)
Hi,
I have a master file that i need to split into multiple files based on matched patterns. sample of my data as follows:-
scaff_1 a e 123 130 c_scaff_100
scaff_1 a e 132 138 c_scaff_101
scaff_1 a e 140 150 ... (2 Replies)
I have a list of patterns (regexes) in a file and use with `grep -f <file_with_list_of_regexes.txt> input.txt` to search in my input for those patterns. grep is doing a fantastic job at it and finds me the matching input text but I also want to see in the output the regex (from... (1 Reply)
I have a file which contains below kind of lines
2013-05-21 00:00:03 INFO moved to unprocessed, as doesn't exist in masklist and modified at 2013-05-20@21:21:21.000000000.
2013-05-21 00:00:03 INFO moved to unprocessed, as doesn't exist in masklist and modified at... (1 Reply)
Hi ,
I have an issue where I want to parse through the output from a file and I want to grab the nth occurrence of text in between two patterns preferably using awk or sed
! TICKET NBR : 1 !GSI : 102 ! 3100.2.112.1 11/06/2013 15:56:29 ! 3100.2.22.3 98 ! 3100.2.134.2... (8 Replies)
Hi,
What is the best approach to grab contents between
Changes
Dependencies
from the following example snippy
Changes in packages about to be updated:
bash-3.2-32.el5_9.1.x86_64
* Thu Jun 27 22:00:00 2013 Roman Rakus <rrakus@redhat.com> - 3.2-32.1
- Fixed a bug that caused... (2 Replies)
Hi,
I need help to match pattern started with "RW" in file 1 and with pattern in $1 in file 2 as follows:-
File 1
BH /TOTAL=466(423); /POSITIVE=300(257); /UNKNOWN=25(25);
BH /F_P=141(141); /F_N=136; /P=4;
CC /TAX=!?; /MAX-R=2;
CC /VER=2;
RW P9610, AR_BSU , T; PAE25, AE_E57... (10 Replies)
Hi,
I am trying to extract some patterns from a line. The input file is space delimited and i could not use column to get value after "IN" or "OUT" patterns as there could be multiple white spaces before the next digits that i need to print in the output file . I need to print 3 patterns in a... (3 Replies)
Hi
I have two lists of patterns named A and B consisting of around 200 entries in each and I want to extract all the sentences from a big text file which match atleast one pattern from both A and B.
For example, pattern list A consists of :
ama
ani
ahum
mari
...
...
and pattern... (1 Reply)
My input looks like this.
# Lot Of CODE Before
AppType_somethinglese=$(cat << EOF
AppType_test1='test-tool/blatest-tool-ear'
AppType_test2='test/blabla-ear'
# Lot Of CODE After
I want to print text betwen 1) _ and = and 2)/ and ' from each line
and exclude lines with "EOF".
Output... (2 Replies)
Discussion started by: kchinnam
2 Replies
LEARN ABOUT PLAN9
regex
regex(1F) FMLI Commands regex(1F)NAME
regex - match patterns against a string
SYNOPSIS
regex [-e] [ -v "string"] [ pattern template] ... pattern [template]
DESCRIPTION
The regex command takes a string from the standard input, and a list of pattern / template pairs, and runs regex() to compare the string
against each pattern until there is a match. When a match occurs, regex writes the corresponding template to the standard output and
returns TRUE. The last (or only) pattern does not need a template. If that is the pattern that matches the string, the function simply
returns TRUE. If no match is found, regex returns FALSE.
The argument pattern is a regular expression of the form described in regex(). In most cases, pattern should be enclosed in single quotes
to turn off special meanings of characters. Note that only the final pattern in the list may lack a template.
The argument template may contain the strings $m0 through $m9, which will be expanded to the part of pattern enclosed in ( ... )$0 through
( ... )$9 constructs (see examples below). Note that if you use this feature, you must be sure to enclose template in single quotes so
that FMLI does not expand $m0 through $m9 at parse time. This feature gives regex much of the power of cut(1), paste(1), and grep(1), and
some of the capabilities of sed(1). If there is no template, the default is $m0$m1$m2$m3$m4$m5$m6$m7$m8$m9.
OPTIONS
The following options are supported:
-e Evaluates the corresponding template and writes the result to the standard output.
-v "string" Uses string instead of the standard input to match against patterns.
EXAMPLES
Example 1: Cutting letters out of a string
To cut the 4th through 8th letters out of a string (this example will output strin and return TRUE):
`regex -v "my string is nice" '^.{3}(.{5})$0' '$m0'`
Example 2: Validating input in a form
In a form, to validate input to field 5 as an integer:
valid=`regex -v "$F5" '^[0-9]+$'`
Example 3: Translating an environment variable in a form
In a form, to translate an environment variable which contains one of the numbers 1, 2, 3, 4, 5 to the letters a, b, c, d, e:
value=`regex -v "$VAR1" 1 a 2 b 3 c 4 d 5 e '.*' 'Error'`
Note the use of the pattern '.*' to mean "anything else".
Example 4: Using backquoted expressions
In the example below, all three lines constitute a single backquoted expression. This expression, by itself, could be put in a menu defini-
tion file. Since backquoted expressions are expanded as they are parsed, and output from a backquoted expression (the cat command, in this
example) becomes part of the definition file being parsed, this expression would read /etc/passwd and make a dynamic menu of all the login
ids on the system.
`cat /etc/passwd | regex '^([^:]*)$0.*$' '
name=$m0
action=`message "$m0 is a user"`'`
DIAGNOSTICS
If none of the patterns match, regex returns FALSE, otherwise TRUE.
NOTES
Patterns and templates must often be enclosed in single quotes to turn off the special meanings of characters. Especially if you use the
$m0 through $m9 variables in the template, since FMLI will expand the variables (usually to "") before regex even sees them.
Single characters in character classes (inside []) must be listed before character ranges, otherwise they will not be recognized. For exam-
ple, [a-zA-Z_/] will not find underscores (_) or slashes (/), but [_/a-zA-Z] will.
The regular expressions accepted by regcmp differ slightly from other utilities (that is, sed, grep, awk, ed, and so forth).
regex with the -e option forces subsequent commands to be ignored. In other words, if a backquoted statement appears as follows:
`regex -e ...; command1; command2`
command1 and command2 would never be executed. However, dividing the expression into two:
`regex -e ...``command1; command2`
would yield the desired result.
ATTRIBUTES
See attributes(5) for descriptions of the following attributes:
+-----------------------------+-----------------------------+
| ATTRIBUTE TYPE | ATTRIBUTE VALUE |
+-----------------------------+-----------------------------+
|Availability |SUNWcsu |
+-----------------------------+-----------------------------+
SEE ALSO awk(1), cut(1), grep(1), paste(1), sed(1), regcmp(3C), attributes(5)SunOS 5.10 12 Jul 1999 regex(1F)