How to extact value of pattern which is not in comment(another pattern) - shell

Extract "value=" only from non-comment portion
See the below sed expression which gets value from commented code as well
I tried with grep but that doesn't work also
#!/bin/sh
#set -x
FILE="/tmp/comment.txt"
create_file () {
echo "/*" > $FILE
echo "this is a multi" >> $FILE
echo "line with" >> $FILE
echo "var=20" >> $FILE
echo "and ending the comment */" >> $FILE
echo "var=15" >> $FILE # line after comment
}
create_file
cat $FILE
# This sed should extract only from var=15 which is not part of
# comments, how to do that?
# output should be only 15, instead of "20 and 15"
sed -n "s/\(var=\)\([0-9]*\)/\2/p" $FILE
Actual:
/*
this is a multi
line with
var=20
and ending the comment */
var=15
20
15
Expected:
/*
this is a multi
line with
var=20
and ending the comment */
var=15
15

This seems to work:
sed -n -e:a -e'/\*\//d;/\/\*/{N;ba
};s/^var=//p'
The easy part is extracting the value from the line; the hard part is removing the comment first. Rough translation: if there's a */ then delete everything; otherwise if there's a /* then read the next line as well and start over; otherwise if the line starts with "var=" then delete that part and print the rest.
Note 1: that annoying line break may not be needed in your version of sed.
Note 2: I advise you to test this on the command line, before you attempt it from within a script.

This is the cheap and cheerful way to remove comments as you've shown using GNU awk for multi-char RS:
$ awk -v RS='[*]/' -v ORS= '{sub("/[*].*","")}1' file
var=15
It'll strip the comments no matter where they start/stop on each line:
$ cat file
here's some text /* here's a comment */ and more text /* bleh */and more /*
this is a multi
line with
ending here */ and more
var=20/*
and ending the comment */
/* commented */ var=15
$ awk -v RS='[*]/' -v ORS= '{sub("/[*].*","")} 1' file
here's some text and more text and more and more
var=20
var=15
It just can't identify strings that look like comment starts/stops inside strings or other language-specific constructs.
You can pipe that to whatever you like to get the value of var. If that's not all you need then get/use a parser for whatever language your commented code is written in, e.g. see https://stackoverflow.com/a/13062682/1745001 for C/C++.

Related

sed insert line after a match only once [duplicate]

UPDATED:
Using sed, how can I insert (NOT SUBSTITUTE) a new line on only the first match of keyword for each file.
Currently I have the following but this inserts for every line containing Matched Keyword and I want it to only insert the New Inserted Line for only the first match found in the file:
sed -ie '/Matched Keyword/ i\New Inserted Line' *.*
For example:
Myfile.txt:
Line 1
Line 2
Line 3
This line contains the Matched Keyword and other stuff
Line 4
This line contains the Matched Keyword and other stuff
Line 6
changed to:
Line 1
Line 2
Line 3
New Inserted Line
This line contains the Matched Keyword and other stuff
Line 4
This line contains the Matched Keyword and other stuff
Line 6
You can sort of do this in GNU sed:
sed '0,/Matched Keyword/s//New Inserted Line\n&/'
But it's not portable. Since portability is good, here it is in awk:
awk '/Matched Keyword/ && !x {print "Text line to insert"; x=1} 1' inputFile
Or, if you want to pass a variable to print:
awk -v "var=$var" '/Matched Keyword/ && !x {print var; x=1} 1' inputFile
These both insert the text line before the first occurrence of the keyword, on a line by itself, per your example.
Remember that with both sed and awk, the matched keyword is a regular expression, not just a keyword.
UPDATE:
Since this question is also tagged bash, here's a simple solution that is pure bash and doesn't required sed:
#!/bin/bash
n=0
while read line; do
if [[ "$line" =~ 'Matched Keyword' && $n = 0 ]]; then
echo "New Inserted Line"
n=1
fi
echo "$line"
done
As it stands, this as a pipe. You can easily wrap it in something that acts on files instead.
If you want one with sed*:
sed '0,/Matched Keyword/s//Matched Keyword\nNew Inserted Line/' myfile.txt
*only works with GNU sed
This might work for you:
sed -i -e '/Matched Keyword/{i\New Inserted Line' -e ':a;n;ba}' file
You're nearly there! Just create a loop to read from the Matched Keyword to the end of the file.
After inserting a line, the remainder of the file can be printed out by:
Introducing a loop place holder :a (here a is an arbitrary name).
Print the current line and fetch the next into the pattern space with the ncommand.
Redirect control back using the ba command which is essentially a goto to the a place holder. The end-of-file condition is naturally taken care of by the n command which terminates any further sed commands if it tries to read passed the end-of-file.
With a little help from bash, a true one liner can be achieved:
sed $'/Matched Keyword/{iNew Inserted Line\n:a;n;ba}' file
Alternative:
sed 'x;/./{x;b};x;/Matched Keyword/h;//iNew Inserted Line' file
This uses the Matched Keyword as a flag in the hold space and once it has been set any processing is curtailed by bailing out immediately.
If you want to append a line after first match only, use AWK instead of SED as below
awk '{print} /Matched Keyword/ && !n {print "New Inserted Line"; n++}' myfile.txt
Output:
Line 1
Line 2
Line 3
This line contains the Matched Keyword and other stuff
New Inserted Line
Line 4
This line contains the Matched Keyword and other stuff
Line 6

Replace some lines in fasta file with appended text using while loop and if/else statement

I am working with a fasta file and need to add line-specific text to each of the headers. So for example if my file is:
>TER1
AGCATGCTAGCTAGTCGACTCGATCGCATGCTC
>TER2
AGCATGCTAGCTAGACGACTCGATCGCATGCTC
>URC1
AGCATGCTAGCTAGTCGACTCGATCGCATGCTC
>URC2
AGCATGCTACCTAGTCGACTCGATCGCATGCTC
>UCR3
AGCATGCTAGCTAGTCGACTCGATGGCATGCTC
I want a while loop that will read through each line; for those with a > at the start, I want to append |population: plus the first three characters after the >. So line one would be:
>TER1|population:TER
etc.
I can't figure out how to make this work. Here my best attempt so far.
filename="testfasta.fa"
while read -r line
do
if [[ "$line" == ">"* ]]; then
id=$(cut -c2-4<<<"$line")
printf $line"|population:"$id"\n" >>outfile
else
printf $line"\n">>outfile
fi
done <"$filename"
This produces a file with the original headers and following line each on a single line.
Can someone tell me where I'm going wrong? My if and else loop aren't working at all!
Thanks!
You could use a while loop if you really want,
but sed would be simpler:
sed -e 's/^>\(...\).*/&|population:\1/' "$filename"
That is, for lines starting with > (pattern: ^>),
capture the next 3 characters (with \(...\)),
and match the rest of the line (.*),
replace with the line as it was (&),
and the fixed string |population:,
and finally the captured 3 characters (\1).
This will produce for your input:
>TER1|population:TER
AGCATGCTAGCTAGTCGACTCGATCGCATGCTC
>TER2|population:TER
AGCATGCTAGCTAGACGACTCGATCGCATGCTC
>URC1|population:URC
AGCATGCTAGCTAGTCGACTCGATCGCATGCTC
>URC2|population:URC
AGCATGCTACCTAGTCGACTCGATCGCATGCTC
>UCR3|population:UCR
AGCATGCTAGCTAGTCGACTCGATGGCATGCTC
Or you can use this awk, also producing the same output:
awk '{sub(/^>.*/, $0 "|population:" substr($0, 2, 3))}1' "$filename"
You can do this quickly in awk:
awk '$1~/^>/{$1=$1"|population:"substr($1,2,3)}{}1' infile.txt > outfile.txt
$ awk '$1~/^>/{$1=$1"|population:"substr($1,2,3)}{}1' testfile
>TER1|population:TER
AGCATGCTAGCTAGTCGACTCGATCGCATGCTC
>TER2|population:TER
AGCATGCTAGCTAGACGACTCGATCGCATGCTC
>URC1|population:URC
AGCATGCTAGCTAGTCGACTCGATCGCATGCTC
>URC2|population:URC
AGCATGCTACCTAGTCGACTCGATCGCATGCTC
>UCR3|population:UCR
AGCATGCTAGCTAGTCGACTCGATGGCATGCTC
Here awk will:
Test if the record starts with a > The $1 looks at the first field, but $0 for the entire record would work just as well in this case. The ~ will perform a regex test, and ^> means "Starts with >". Making the test: ($1~/^>/)
If so it will set the first field to the output you are looking for (using substr() to get the bits of the string you want. {$1=$1"|population:"substr($1,2,3)}
Finally it will print out the entire record (with the changes if applicable): {}1 which is shorthand for {print $0} or.. print the entire record.

Comment out line, only if previous line contains matching string

Looking for a solution for a bash script using sed or awk to comment out a line, only if the previous line contains a matching string.
For example, a file containing:
...
if [ $V1 -gt 100 ]; then
some specific commands
else
some other specific commands
fi
...
I'd like to comment out the line containing else but ONLY if the previous line contains specific.
I've attempted piping multiple sed commands along with grep commands to no avail.
sed -E '/specific/{n;s/^([[:blank:]]*)else$/\1#else/}'
Output
...
if [ $V1 -gt 100 ]; then
some specific commands
#else
some other commands
fi
...
A retrospection
/specific/ look for the line containing the pattern specific
n add the next line to the pattern space. n auto prints the current pattern space.
Check if the next line is (one_or_more_spaces)else,if yes, substitute the line with a (one_or_more_spaces_found_previously)#else. Remember () is for pattern reuse and \1 is the previously matched pattern reused.
-E enable extended regex
-i is for inplace edit of the actual file
You can use this awk solution:
awk '/specific/{p=NR} NR==p+1{p=0; if (/^[[:blank:]]*else/) $0 = "#" $0} 1' file
if [ $V1 -gt 100 ]; then
some specific commands
#else
some other commands
fi
In this block /specific/p=NR we find specific and store current line # in p
Next block is executed for very next line due to p == NR+1 condition
We rest p=0 and if that line has else at start with optional whitespaces before we just comment it out.

appending text to specific line in file bash

So I have a file that contains some lines of text separated by ','. I want to create a script that counts how much parts a line has and if the line contains 16 parts i want to add a new one. So far its working great. The only thing that is not working is appending the ',' at the end. See my example below:
Original file:
a,a,a,a,a,a,a,a,a,a,a,a,a,a,a,a
b,b,b,b,b,b
a,a,a,a,a,a,a,a,a,a,a,a,a,a,a,a,a
b,b,b,b,b,b
a,a,a,a,a,a,a,a,a,a,a,a,a,a,a,a
Expected result:
a,a,a,a,a,a,a,a,a,a,a,a,a,a,a,a,xx
b,b,b,b,b,b
a,a,a,a,a,a,a,a,a,a,a,a,a,a,a,a,a
b,b,b,b,b,b
a,a,a,a,a,a,a,a,a,a,a,a,a,a,a,a,xx
This is my code:
while read p; do
if [[ $p == "HEA"* ]]
then
IFS=',' read -ra ADDR <<< "$p"
echo ${#ADDR[#]}
arrayCount=${#ADDR[#]}
if [ "${arrayCount}" -eq 16 ];
then
sed -i "/$p/ s/\$/,xx/g" $f
fi
fi
done <$f
Result:
a,a,a,a,a,a,a,a,a,a,a,a,a,a,a,a
,xx
b,b,b,b,b,b
a,a,a,a,a,a,a,a,a,a,a,a,a,a,a,a,a
b,b,b,b,b,b
a,a,a,a,a,a,a,a,a,a,a,a,a,a,a,a
,xx
What im doing wrong? I'm sure its something small but i cant find it..
It can be done using awk:
awk -F, 'NF==16{$0 = $0 FS "xx"} 1' file
a,a,a,a,a,a,a,a,a,a,a,a,a,a,a,a,xx
b,b,b,b,b,b
a,a,a,a,a,a,a,a,a,a,a,a,a,a,a,a,a
b,b,b,b,b,b
a,a,a,a,a,a,a,a,a,a,a,a,a,a,a,a,xx
-F, sets input field separator as comma
NF==16 is the condition that says execute block inside { and } if # of fields is 16
$0 = $0 FS "xx" appends xx at end of line
1 is the default awk action that means print the output
For using sed answer should be in the following:
Use ${line_number} s/..../..../ format - to target a specific line, you need to find out the line number first.
Use the special char & to denote the matched string
The sed statement should look like the following:
sed -i "${line_number}s/.*/&xx/"
I would prefer to leave it to you to play around with it but if you would prefer i can give you a full working sample.

Print text between two strings on the same line

I've been searching for a ling time, and have not been able to find a working answer for my problem.
I have a line from an HTML file extracted with sed '162!d' skinlist.html, which contains the text
<a href="/skin/dwarf-red-beard-734/" title="Dwarf Red Beard">.
I want to extract the text Dwarf Red Beard, but that text is modular (can be changed), so I would like to extract the text between title=" and ".
I cannot, for the life of me, figure out how to do this.
awk 'NR==162 {print $4}' FS='"' skinlist.html
set field separator to "
print only line 162
print field 4
Solution in sed
sed -n '162 s/^.*title="\(.*\)".*$/\1/p' skinlist.html
Extracts line 162 in skinlist.html and captures the title attributes contents in\1.
The shell's variable expansion syntax allows you to trim prefixes and suffixes from a string:
line="$(sed '162!d' skinlist.html)" # extract the relevant line from the file
temp="${line#* title=\"}" # remove from the beginning through the first match of ' title="'
if [ "$temp" = "$line" ]; then
echo "title not found in '$line'" >&2
else
title="${temp%%\"*}" # remote from the first '"' through the end
fi
You can pass it through another sed or add expressions to that sed like -e 's/.*title="//g' -e 's/">.*$//g'
also sed
sed -n '162 s/.*"\([a-zA-Z ]*\)"./\1/p' skinlist.html

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