I'm a beginner to sed. I know that it's possible to apply a command (or a set of commands) to a certain range of lines like so
sed '/[begin]/,/[end]/ [some command]'
where [begin] is a regular expression that designates the beginning line of the range and [end] is a regular expression that designates the ending line of the range (but is included in the range).
I'm trying to use this to specify a range of lines in a file and join them all into one line. Here's my best try, which didn't work:
sed '/[begin]/,/[end]/ {
N
s/\n//
}
'
I'm able to select the set of lines I want without any problem, but I just can't seem to merge them all into one line. If anyone could point me in the right direction, I would be really grateful.
One way using GNU sed:
sed -n '/begin/,/end/ { H;g; s/^\n//; /end/s/\n/ /gp }' file.txt
This is straight forward if you want to select some lines and join them. Use Steve's answer or my pipe-to-tr alternative:
sed -n '/begin/,/end/p' | tr -d '\n'
It becomes a bit trickier if you want to keep the other lines as well. Here is how I would do it (with GNU sed):
join.sed
/\[begin\]/ {
:a
/\[end\]/! { N; ba }
s/\n/ /g
}
So the logic here is:
When [begin] line is encountered start collecting lines into pattern space with a loop.
When [end] is found stop collecting and join the lines.
Example:
seq 9 | sed -e '3s/^/[begin]\n/' -e '6s/$/\n[end]/' | sed -f join.sed
Output:
1
2
[begin] 3 4 5 6 [end]
7
8
9
I like your question. I also like Sed. Regrettably, I do not know how to answer your question in Sed; so, like you, I am watching here for the answer.
Since no Sed answer has yet appeared here, here is how to do it in Perl:
perl -wne 'my $flag = 0; while (<>) { chomp; if (/[begin]/) {$flag = 1;} print if $flag; if (/[end]/) {print "\n" if $flag; $flag = 0;} } print "\n" if $flag;'
Related
I need to replace all occurrences of a string after nth occurrence in every line of a Unix file.
My file data:
:account_id:12345:6789:Melbourne:Aus
:account_id:98765:43210:Adelaide:Aus
My output data:
:account_id:123456789MelbourneAus
:account_id:9876543210AdelaideAus
tried using sed: sed 's/://3g' test.txt
Unfortunately, the g option with the occurrence is not working as expected. instead, it is replacing all the occurrences.
Another approach using awk
awk -v c=':' -v n=2 'BEGIN{
FS=OFS=""
}
{
j=0;
for(i=0; ++i<=NF;)
if($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($0,1,RLENGTH) tgt } 1' file
:account_id:123456789MelbourneAus
:account_id:9876543210AdelaideAus
I have a problem with replacing string.
|Stm=2|Seq=2|Num=2|Svc=101|MsgSize(514)=514|MsgType=556|SymbolIndex=16631
I want to find occurrence of Svc till | appears and swap place with Stm till | appears.
My attempts went to replacing characters and this is not my goal.
awk -F'|' -v OFS='|'
'{a=b=0;
for(i=1;i<=NF;i++){a=$i~/^Stm=/?i:a;b=$i~/^Svc=/?i:b}
t=$a;$a=$b;$b=t}7' file
outputs:
|Svc=101|Seq=2|Num=2|Stm=2|MsgSize(514)=514|MsgType=556|SymbolIndex=16631
the code exchange the column of Stm.. and Svc.., no matter which one comes first.
If perl solution is okay, assumes only one column matches each for search terms
$ cat ip.txt
|Stm=2|Seq=2|Num=2|Svc=101|MsgSize(514)=514|MsgType=556|SymbolIndex=16631
$ perl -F'\|' -lane '
#i = grep { $F[$_] =~ /Svc|Stm/ } 0..$#F;
$t=$F[$i[0]]; $F[$i[0]]=$F[$i[1]]; $F[$i[1]]=$t;
print join "|", #F;
' ip.txt
|Svc=101|Seq=2|Num=2|Stm=2|MsgSize(514)=514|MsgType=556|SymbolIndex=16631
-F'\|' -lane split input line on |, see also Perl flags -pe, -pi, -p, -w, -d, -i, -t?
#i = grep { $F[$_] =~ /Svc|Stm/ } 0..$#F get index of columns matching Svc and Stm
$t=$F[$i[0]]; $F[$i[0]]=$F[$i[1]]; $F[$i[1]]=$t swap the two columns
Or use ($F[$i[0]], $F[$i[1]]) = ($F[$i[1]], $F[$i[0]]); courtesy How can I swap two Perl variables
print join "|", #F print the modified array
You need to use capture groups and backreferences in a string substition.
The below will swap the 2:
echo '|Stm=2|Seq=2|Num=2|Svc=101|MsgSize(514)=514|MsgType=556|SymbolIndex=16631' | sed 's/\(Stm.*|\)\(.*\)\(Svc.*|\)/\3\2\1/'
As pointed out in the comment from #Kent, this will not work if the strings were not in that order.
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 would be happy if anyone can suggest me command (sed or AWK one line command) to divide each line of file in equal number of part. For example divide each line in 4 part.
Input:
ATGCATHLMNPHLNTPLML
Output:
ATGCA THLMN PHLNT PLML
This should work using GNU sed:
sed -r 's/(.{4})/\1 /g'
-r is needed to use extended regular expressions
.{4} captures every four characters
\1 refers to the captured group which is surrounded by the parenthesis ( ) and adds a space behind this group
g makes sure that the replacement is done as many times as possible on each line
A test; this is the input and output in my terminal:
$ echo "ATGCATHLMNPHLNTPLML" | sed -r 's/(.{4})/\1 /g'
ATGC ATHL MNPH LNTP LML
I suspect awk is not the best tool for this, but:
gawk --posix '{ l = sprintf( "%d", 1 + (length()-1)/4);
gsub( ".{"l"}", "& " ) } 1' input-file
If you have a posix compliant awk you can omit the --posix, but --posix is necessary for gnu awk and since that seems to be the most commonly used implementation I've given the solution in terms of gawk.
This might work for you (GNU sed):
sed 'h;s/./X/g;s/^\(.*\)\1\1\1/\1 \1 \1 \1/;G;s/\n/&&/;:a;/^\n/bb;/^ /s/ \(.*\n.*\)\n\(.\)/\1 \n\2/;ta;s/^.\(.*\n.*\)\n\(.\)/\1\2\n/;ta;:b;s/\n//g' file
Explanation:
h copy the pattern space (PS) to the hold space (HS)
s/./X/g replace every character in the HS with the same non-space character (in this case X)
s/^\(.*\)\1\1\1/\1 \1 \1 \1/ split the line into 4 parts (space separated)
G append a newline followed by the contents of the HS to the PS
s/\n/&&/ double the newline (to be later used as markers)
:a introduce a loop namespace
/^\n/bb if we reach a newline we are done and branch to the b namespace
/^ /s/ \(.*\n.*\)\n\(.\)/\1 \n\2/;ta; if the first character is a space add a space to the real line at this point and repeat
s/^.\(.*\n.*\)\n\(.\)/\1\2\n/;ta any other character just bump along and repeat
:b;s/\n//g all done just remove the markers and print out the result
This work for any length of line, however is the line is not exactly divisible by 4 the last portion will contain the remainder as well.
perl
perl might be a better choice here:
export cols=4
perl -ne 'chomp; $fw = 1 + int length()/$ENV{cols}; while(/(.{1,$fw})/gm) { print $1 . " " } print "\n"'
This re-calculates field-width for every line.
coreutils
A GNU coreutils alternative, field-width is chosen based on the first line of infile:
cols=4
len=$(( $(head -n1 infile | wc -c) - 1 ))
fw=$(echo "scale=0; 1 + $len / 4" | bc)
cut_arg=$(paste -d- <(seq 1 $fw 19) <(seq $fw $fw $len) | head -c-1 | tr '\n' ',')
Value of cut_arg is in the above case:
1-5,6-10,11-15,16-
Now cut the line into appropriate chunks:
cut --output-delimiter=' ' -c $cut_arg infile
I am not very proficient in perl, awk, or sed and I have been searching the web for a solution to my problem for some while now, but wasn't very successful.
I would like to replace
<math> ... </math>
with
<math>\begin{align} ... \end{align}</math>
if ... contains \\. My problem is that the string between the <math> tags can span multiple lines. I managed to replace the tags within one line with sed but couldn't get it to run for multiple lines.
Any simple solution with perl, awk, or sed is very welcome. Thanks a lot.
Use separate expressions for each tag and the script will be immune to multilinedness:
sed -e 's,<math>,&\\begin{align},g' -e 's,</math>,&\\end{align},g'
Edit:
Multiline awk version:
awk '/<math>/,/<\/math>/ {
if (index($0, "<math>")) {
a=$0
} else {
b = b $0
}
if (index($0, "</math>")) {
if (index(b,"\\\\")) {
sub("<math>","&\\begin{align}", a)
sub("</math>","\\end{align}&", b)
};
print a,b
a=""
b=""
}
}'
Try next perl command. How it works? It reads content file in slurp mode saving it in $f variable and later add with a regexp in single mode (match newlines with .) \begin{regex} and \end{regex} if found \\ between math tags.
perl -e '
do {
$/ = undef;
$f = <>
};
$f =~ s#(<math>)(.*\\\\.*)(</math>)#$1\\begin{align}$2\\end{align}$3#s;
printf qq|%s|, $f
' infile
This might work for you (GNU sed):
sed ':a;$!{N;ba}
/[\x00\x01\x02]/q1
s/<math>/\x00/g
s/<\/math>/\x01/g
s/\\\\/\x02/g
s/\x00\([^\x01\x02]*\)\x01/<math>\1<\/math>/g
s/\x00/<math>\\begin{align}/g
s/\x01/\\end{align}<\/math>/g
s/\x02/\\\\/g' file