Can anyone help me figure out how to do this, it would be much appreciated.
example
block of //delete
non-important text //delete
important text //keep
more important text //keep
sed '1,/^$/d' file
or
awk '!$0{f=1;next}f{print}' file
Output
$ sed '1,/^$/d' <<< $'block of\nnon-important text\n\nimportant text\nmore important text'
important text
more important text
$ awk '!$0{f=1;next}f{print}' <<< $'block of\nnon-important text\n\nimportant text\nmore important text'
important text
more important text
If the blank line is empty, this'll do it:
sed '1,/^$/d' filename
with awk:
awk "BEGIN { x = 0 } /^$/ { x = 1} { if (x == 2) { print } ; if (x == 1) { x = 2 } }" filename
Another option with grep (working on lines)
grep -v PATTERN filename > newfilename
For example:
filename has the following lines:
this is not implicated but important text
this is not important text
this is important text he says
not important text he says
not this it is more important text
A filter of:
grep -v "not imp" filename > newfilename
would create newfilename with the following 3 lines:
this is not implicated but important text
this is important text he says
not this it is more important text
You would have to choose a PATTERN that would uniquely identify the lines you are trying to remove. If you use a PATTERN of "important text", it would match all of the lines while "not imp" only matches the lines that have the words "not imp" in them. Use egrep (or grep -E) for regexp filters if you want more flexibility in pattern matching.
Related
I need to replace all occurrences of a string after nth occurrence in every line of a Unix file.
My file data:
:account_id:12345:6789:Melbourne:Aus
:account_id:98765:43210:Adelaide:Aus
My output data:
:account_id:123456789MelbourneAus
:account_id:9876543210AdelaideAus
tried using sed: sed 's/://3g' test.txt
Unfortunately, the g option with the occurrence is not working as expected. instead, it is replacing all the occurrences.
Another approach using awk
awk -v c=':' -v n=2 'BEGIN{
FS=OFS=""
}
{
j=0;
for(i=0; ++i<=NF;)
if($i==c && j++>=n)$i=""
}1' file
$ cat file
:account_id:12345:6789:Melbourne:Aus
:account_id:98765:43210:Adelaide:Aus
$ awk -v c=':' -v n=2 'BEGIN{FS=OFS=""}{j=0;for(i=0; ++i<=NF;)if($i==c && j++>=n)$i=""}1' file
:account_id:123456789MelbourneAus
:account_id:9876543210AdelaideAus
With GNU awk, using gensub please try following. This is completely based on your shown samples, where OP wants to remove : from 3rd occurrence onwards. Using gensub to segregate parts of matched values and removing all colons from 2nd part(from 3rd colon onwards) in it as per OP's requirement.
awk -v regex="^([^:]*:)([^:]*:)(.*)" '
{
firstPart=restPart=""
firstPart=gensub(regex, "\\1 \\2", "1", $0)
restPart=gensub(regex,"\\3","1",$0)
gsub(/:/,"",restPart)
print firstPart restPart
}
' Input_file
I have inferred based on the limited data you've given us, so it's possible this won't work. But I wouldn't use regex for this job. What you have there is colon delimited fields.
So I'd approach it using split to extract the data, and then some form of string formatting to reassemble exactly what you like:
#!/usr/bin/perl
use strict;
use warnings;
while (<DATA>) {
chomp;
my ( undef, $first, #rest ) = split /:/;
print ":$first:", join ( "", #rest ),"\n";
}
__DATA__
:account_id:12345:6789:Melbourne:Aus
:account_id:98765:43210:Adelaide:Aus
This gives you the desired result, whilst IMO being considerably clearer for the next reader than a complicated regex.
You can use the perl solution like
perl -pe 's~^(?:[^:]*:){2}(*SKIP)(?!)|:~~g if /^:account_id:/' test.txt
See the online demo and the regex demo.
The ^(?:[^:]*:){2}(*SKIP)(?!)|: regex means:
^(?:[^:]*:){2}(*SKIP)(?!) - match
^ - start of string (here, a line)
(?:[^:]*:){2} - two occurrences of any zero or more chars other than a : and then a : char
(*SKIP)(?!) - skip the match and go on to search for the next match from the failure position
| - or
: - match a : char.
And only run the replacement if the current line starts with :account_id: (see if /^:account_id:/').
Or an awk solution like
awk 'BEGIN{OFS=FS=":"} /^:account_id:/ {result="";for (i=1; i<=NF; ++i) { result = result (i > 2 ? $i : $i OFS)}; print result}' test.txt
See this online demo. Details:
BEGIN{OFS=FS=":"} - sets the input/output field separator to :
/^:account_id:/ - line must start with :account_id:
result="" - sets result variable to an empty string
for (i=1; i<=NF; ++i) { result = result (i > 2 ? $i : $i OFS)}; print result} - iterates over the fields and if the field number is greater than 2, just append the current field value to result, else, append the value + output field separator; then print the result.
I would use GNU AWK following way if n fixed and equal 2 following way, let file.txt content be
:account_id:12345:6789:Melbourne:Aus
:account_id:98765:43210:Adelaide:Aus
then
awk 'BEGIN{FS=":";OFS=""}{$2=FS $2 FS;print}' file.txt
output
:account_id:123456789MelbourneAus
:account_id:9876543210AdelaideAus
Explanation: use : as field separator and nothing as output field separator, this itself does remove all : so I add : which have to be preserved: 1st (before second column) and 2nd (after second column). Beware that I tested it solely for this data, so if you would want to use it you should firstly test it with more possible inputs.
(tested in gawk 4.2.1)
This might work for you (GNU sed):
sed 's/:/\n/3;h;s/://g;H;g;s/\n.*\n//' file
Replace the third occurrence of : by a newline.
Make a copy of the line.
Delete all occurrences of :'s.
Append the amended line to the copy.
Join the two lines by removing everything from third occurrence of the copy to the third occurrence of the amended line.
N.B. The use of the newline is the best delimiter to use in the case of sed, as the line presented to seds commands are initially devoid of newlines. However the important property of the delimiter is that it is unique and therefore can be any such character as long as it is not found anywhere in the data set.
An alternative solution uses a loop to remove all :'s after the first two:
sed -E ':a;s/^(([^:]*:){2}[^:]*):/\1/;ta' file
With GNU awk for the 3rd arg to match() and gensub():
$ awk 'match($0,/(:[^:]+:)(.*)/,a){ $0=a[1] gensub(/:/,"","g",a[2]) } 1' file
:account_id:123456789MelbourneAus
:account_id:9876543210AdelaideAus
and with any awk in any shell on every Unix box:
$ awk 'match($0,/:[^:]+:/){ tgt=substr($0,1+RLENGTH); gsub(/:/,"",tgt); $0=substr($0,1,RLENGTH) tgt } 1' file
:account_id:123456789MelbourneAus
:account_id:9876543210AdelaideAus
What is this sed command doing? and is there any online utility that kind of explains sed a little bit, like regex?
sed -i '1s/$/|,a Type,b Type,c Type/;/./!b;1!s/$/|,,,/' textflile.txt
I think in the beginning it is adding csv a type, b type, c type at the end of the line but what does the rest of the command too
I don't know of any such utility, but let me explain using a text editor:
sed -i '1s/$/|,a Type,b Type,c Type/;/./!b;1!s/$/|,,,/' textflile.txt
^ ^ ^ ^ ^^ ^^ ^
| | | | || || |
modify | End Non-empty || || input
the | of lines || |Negation, file
file | line only || |i.e. lines 2,3,...
in | || |
place | || First
First line Negation, i.e.| line
empty lines only|
Branch to
script end,
i.e. skip the rest
In other words, it adds |,a type, b Type,c Type to the first line, doesn't change empty lines, and adds |,,, to all the remaining lines.
sed -i '1s/$/|,a Type,b Type,c Type/;/./!b;1!s/$/|,,,/' textflile.txt
can be written as
sed -i '
1 s/$/|,a Type,b Type,c Type/
/./! b
1! s/$/|,,,/
' textflile.txt
on line 1 only, add some text to the end of the line
if the line is empty ("matches 1 character, not"), goto next "cycle" (i.e., print current line and go to next line)
on every line except line 1, add "|,,," to the end of the line
So, it looks like you're adding some blank fields to a CSV file.
info sed contains the complete sed manual.
This doesn't answer your question but it's important for people to know and requires more space and formatting than a comment so: FYI to do what #choroba says that sed script does, i.e.
it adds |,a type, b Type,c Type to the first line,
doesn't change empty lines,
and adds |,,, to all the remaining lines.
is just this in awk:
awk '
NR==1 { print $0 "|,a type, b Type,c Type"; next }
!NF { print }
NF { print $0 "|,,," }
'
or if you're familiar with ternary expressions and want to remove the redundant code:
awk '{
sfx = "|," (NR==1 ? "a type, b Type,c Type" : ",,")
print $0 (NF ? sfx : "")
}'
What is a sed script that will remove the "\n" character but only if it is inside "" characters (delimited string), not the \n that is actually at the end of the (virtual) line?
For example, I want to turn this file
"lalala","lalalslalsa"
"lalalala","lkjasjdf
asdfasfd"
"lalala","dasdf"
(line 2 has an embedded \n ) into this one
"lalala","lalalslalsa"
"lalalala","lkjasjdf \\n asdfasfd"
"lalala","dasdf"
(Line 2 and 3 are now joined, and the real line feed was replaced with the character string \\n (or any other easy to spot character string, I'm not picky))
I don't just want to remove every other newline as a previous question asked, nor do I want to remove ALL newlines, just those that are inside quotes. I'm not wedded to sed, if awk would work, that's fine too.
The file being operated on is too large to fit in memory all at once.
sed is an excellent tool for simple substitutions on a single line but for anything else you should use awk., e.g:
$ cat tst.awk
{
if (/"$/) {
print prev $0
prev = ""
}
else {
prev = prev $0 " \\\\n "
}
}
$ awk -f tst.awk file
"lalala","lalalslalsa"
"lalalala","lkjasjdf \\n asdfasfd"
"lalala","dasdf"
Below was my original answer but after seeing #NeronLeVelu's approach of just testing for a quote at the end of the line I realized I was doing this in a much too complicated way. You could just replace gsub(/"/,"&") % 2 below with /"$/ and it'd work the same but the above code is a simpler implementation of the same functionality and will now handle embedded escaped double quotes as long as they aren't at the end of a line.
$ cat tst.awk
{ $0 = saved $0; saved="" }
gsub(/"/,"&") % 2 { saved = $0 " \\\\n "; next }
{ print }
$ awk -f tst.awk file
"lalala","lalalslalsa"
"lalalala","lkjasjdf \\n asdfasfd"
"lalala","dasdf"
The above only stores 1 output line in memory at a time. It just keeps building up an output line from input lines while the number of double quotes in that output line is an odd number, then prints the output line when it eventually contains an even number of double quotes.
It will fail if you can have double quotes inside your quoted strings escaped as \", not "", but you don't show that in your posted sample input so hopefully you don't have that situation. If you have that situation you need to write/use a real CSV parser.
sed -n ':load
/"$/ !{N
b load
}
:cycle
s/^\(\([^"]*"[^"]*"\)*\)\([^"]*"[^"]*\)\n/\1\3 \\\\n /
t cycle
p' YourFile
load the lines in working buffer until a close line (ending with ") is found or end reach
replace any \n that is after any couple of open/close " followed by a single " with any other caracter that " between from the start of file by the escapped version of new line (in fact replace starting string + \n by starting string and escaped new line)
if any substitution occur, retry another one (:cycle and t cycle)
print the result
continue until end of file
thanks to #Ed Morton for remark about escaped new line
I want to read from the file /etc/lvm/lvm.conf and check for the below pattern that could span across multiple lines.
tags {
hosttags = 1
}
There could be as many white spaces between tags and {, { and hosttags and so forth. Also { could follow tags on the next line instead of being on the same line with it.
I'm planning to use awk and sed to do this.
While reading the file lvm.conf, it should skip empty lines and comments.
That I'm doing using.
data=$(awk < cat `cat /etc/lvm/lvm.conf`
/^#/ { next }
/^[[:space:]]*#/ { next }
/^[[:space:]]*$/ { next }
.
.
How can I use sed to find the pattern I described above?
Are you looking for something like this
sed -n '/{/,/}/p' input
i.e. print lines between tokens (inclusive)?
To delete lines containing # and empty lines or lines containing only whitespace, use
sed -n '/{/,/}/p' input | sed '/#/d' | sed '/^[ ]*$/d'
space and a tab--^
update
If empty lines are just empty lines (no ws), the above can be shortened to
sed -e '/#/d' -e '/^$/d' input
update2
To check if the pattern tags {... is present in file, use
$ tr -d '\n' < input | grep -o 'tags\s*{[^}]*}'
tags { hosttags = 1# this is a comment}
The tr part above removes all newlines, i.e. makes everything into one single line (will work great if the file isn't to large) and then search for the tags pattern and outputs all matches.
The return code from grep will be 0 is pattern was found, 1 if not.
Return code is stored in variable $?. Or pipe the above to wc -l to get the number of matches found.
update3
regex for searcing for tags { hosttags=1 } with any number of ws anywhere
'tags\s*{\s*hosttags\s*=\s*1*[^}]*}'
try this line:
awk '/^\s*#|^\s*$/{next}1' /etc/lvm/lvm.conf
One could try preprocessing the file first, removing commments and empty lines and introducing empty lines behind the closing curly brace for easy processing with the second awk.
awk 'NF && $1!~/^#/{print; if(/}/) print x}' file | awk '/pattern/' RS=
I need help with using sed to comment a matching lines and 4 lines which follows it.
in a text file.
my text file is like this:
[myprocess-a]
property1=1
property2=2
property3=3
property4=4
[anotherprocess-b]
property1=gffgg
property3=gjdl
property2=red
property4=djfjf
[myprocess-b]
property1=1
property4=4
property2=2
property3=3
I want to prefix # to all the lines having text '[myprocess' and 4 lines that follows it
expected output:
#[myprocess-a]
#property1=1
#property2=2
#property3=3
#property4=4
[anotherprocess-b]
property1=gffgg
property3=gjdl
property2=red
property4=djfjf
#[myprocess-b]
#property1=1
#property4=4
#property2=2
#property3=3
Greatly appreciate your help on this.
You can do this by applying a regular expression to a set of lines:
sed -e '/myprocess/,+4 s/^/#/'
This matches lines with 'myprocess' and the 4 lines after them. For those 4 lines it then inserts a '#' at the beginning of the line.
(I think this might be a GNU extension - it's not in any of the "sed one liner" cheatsheets I know)
sed '/\[myprocess/ { N;N;N;N; s/^/#/gm }' input_file
Using string concatenation and default action in awk.
http://www.gnu.org/software/gawk/manual/html_node/Concatenation.html
awk '/myprocess/{f=1} f>5{f=0} f{f++; $0="#" $0} 1' foo.txt
or if the block always ends with empty line
awk '/myprocess/{f=1} !NF{f=0} f{$0="#" $0} 1' foo.txt