Removing cruft lines with sed - regex

How can you write a single sed command that will remove lines that contain any of several regular expressions?
For example I want sed to remove "/./. ::", ":: ", "::foo", and "^^bar" from a document.
As of now, when I run
sed -ir '/ "//.//. ::|:: _|::foo_|^^bar" /d' text.file
the response is "unknown command '/'".
This is the case with or without the inner "s around the regex:
sed -ir '/ //.//. ::|:: _|::foo_|^^bar /d' text.file
Also if I remove the escape(/) before the '/' such as:
sed -ir '/ "/./. ::|:: _|::foo_|^^bar" /d' text.file
the return becomes "unknown command '.'"

You should be using the escape symbol: \
And there's no need to quote the pattern match or add underscores, simply try:
sed -i -r '/\/.\/. ::|:: |::foo|\^\^bar/d' file.txt
Also, you may want to consider escaping the . symbols. The dot would otherwise match any character.
HTH

sed '{
s/::foo_//
s/\^\^bar//
s!/./. ::!!
s/:: _//
}' input_file
To totally delete lines containing patterns:
sed '{
/::foo_/d
/\^\^bar/d
\!/./. ::!d
/:: _/d
}' input_file

Related

Why does this regex work in grep but not sed?

I have two regular expressions:
$ grep -E '\-\- .*$' *.sql
$ sed -E '\-\- .*$' *.sql
(I am trying to grep lines in sql files that have comments and remove lines in sql files that have comments)
The grep command works using this regex; however, the sed returns the following error:
sed: -e expression #1, char 7: unterminated address regex
What am I doing incorrectly with sed?
(The space after the two hyphens is required for sql comments if you are unfamiliar with MySql comments of this type)
You're trying to use:
sed -E '\-\- .*$' *.sql
Here sed command is not correct because you're not really telling sed to do something.
It should be:
sed -n '/-- /p' *.sql
and equivalent grep would be:
grep -- '-- ' *.sql
or even better with a fixed string search:
grep -F -- '-- ' *.sql
Using -- to separate pattern and arguments in grep command.
There is no need to escape - in a regex if it is outside bracket expression (or character class) i.e. [...].
Based on comments below it seems OP's intent is to remove commented section in all *.sql files that start with 2 hyphens.
You may use this sed for that:
sed -i 's/-- .*//g' *.sql
The problem here is not the regex, the problem is that sed requires a command. The equivalent of your grep would be:
sed -n '/\-\- .*$/p'
You suppress output for non-matching lines -n ... you search (wrap your regex in slashes) and you print p (after the last slash).
P.S.: As Anub pointed out, escaping the hyphens - inside the regex is unnecessary.
You are trying to use sed's \cregexpc syntax where with \-<...> you are telling sed the delimiter character you want use is a dash -, but you didn't terminate it where it should be: \-<...>- also add d command to delete those lines.
sed '\-\-\-.*$-d' infile
see man sed about that:
\cregexpc
Match lines matching the regular expression regexp. The c may be any character.
if default / was used this was not required so:
sed '/--.*$/d' infile
or simply:
sed '/^--/d' infile
and more accurately:
sed '/^[[:blank:]]*--/d' infile

How to remove special characters like a single quote from a string?

Using Sed I tried but it did not worked out.
Basically, I have a string say:-
Input:-
'http://www.google.com/photos'
Output required:-
http://www.google.com
I tried using sed but escaping ' is not possible.
what i did was:-
sed 's/\'//' | sed 's/photos//'
sed for photos worked but for ' it didn't.
Please suggest what can be the solution.
Escaping ' in sed is possible via a workaround:
sed 's/'"'"'//g'
# |^^^+--- bash string with the single quote inside
# | '--- return to sed string
# '------- leave sed string and go to bash
But for this job you should use tr:
tr -d "'"
Perl Replacements have a syntax identical to sed, works better than sed, is installed almost in every system by default and works for all machines the same way (portability):
$ echo "'http://www.google.com/photos'" |perl -pe "s#\'##g;s#(.*//.*/)(.*$)#\1#g"
http://www.google.com/
Mind that this solution will keep only the domain name with http in front, discarding all words following http://www.google.com/
If you want to do it with sed , you can use sed "s/'//g" as advised by Wiktor Stribiżew in comments.
PS: I sometimes refer to special chars with their ascii hex code of the special char as advised by man ascii, which is \x27 for '
So for sed you can do it:
$ echo "'http://www.google.com/photos'" |sed -r "s#'##g; s#(.*//.*/)(.*$)#\1#g;"
http://www.google.com/
# sed "s#\x27##g' will also remove the single quote using hex ascii code.
$ echo "'http://www.google.com/photos'" |sed -r "s#'##g; s#(.*//.*)(/.*$)#\1#g;"
http://www.google.com #Without the last slash
If your string is stored in a variable, you can achieve above operations with pure bash, without the need of external tools like sed or perl like this:
$ a="'http://www.google.com/photos'" && a="${a:1:-1}" && echo "$a"
http://www.google.com/photos
# This removes 1st and last char of the variable , whatever this char is.
$ a="'http://www.google.com/photos'" && a="${a:1:-1}" && echo "${a%/*}"
http://www.google.com
#This deletes every char from the end of the string up to the first found slash /.
#If you need the last slash you can just add it to the echo manually like echo "${a%/*}/" -->http://www.google.com/
It's unclear if the ' are actually around your string, although this should take care it:
str="'http://www.google.com/photos'"
echo "$str" | sed s/\'//g | sed 's/\/photos//g'
Combined:
echo "$str" | sed -e "s/'//g" -e 's/\/photos//g'
Using tr:
echo "$str" | sed -e "s/\/photos//g" | tr -d \'
Result:
http://www.google.com
If the single quotes are not around your string it should work regardless.

How to remove a space between matching words?

I've read a lot of questions about how to replace spaces from a file but I have the following problem:
I have a file like so:
<foo>"crazy foo"</foo> <bar>dull-bar</bar>
and I'm trying to remove spaces between > < and only those ones so the file would be like:
`<foo>"crazy foo"</foo><bar>dull-bar</bar>`
So far I've tried to remove then by using sed and tr. Sed is not working by any chance and using tr '> <' '><' outputs:
<foo>"crazy foo"</foo><<bar>dull-bar</bar>
sed -i -e "s/> *</></g" YourFile
-i means YourFile is modified. Remove this option to test your command and display the result in shell output.
* matches n spaces.
The g at the end of sed expression means "Replace all the occurrences".
You could try something like this
echo "<foo>"crazy foo"</foo> <bar>dull-bar</bar>" | sed 's/>[[:space:]]*</></g '
awk -F"\"" '{print $3}' file.txt | sed 's/ //g'

Extract few matching strings from matching lines in file using sed

I have a file with strings similar to this:
abcd u'current_count': u'2', u'total_count': u'3', u'order_id': u'90'
I have to find current_count and total_count for each line of file. I am trying below command but its not working. Please help.
grep current_count file | sed "s/.*\('current_count': u'\d+'\).*/\1/"
It is outputting the whole line but I want something like this:
'current_count': u'3', 'total_count': u'3'
It's printing the whole line because the pattern in the s command doesn't match, so no substitution happens.
sed regexes don't support \d for digits, or x+ for xx*. GNU sed has a -r option to enable extended-regex support so + will be a meta-character, but \d still doesn't work. GNU sed also allows \+ as a meta-character in basic regex mode, but that's not POSIX standard.
So anyway, this will work:
echo -e "foo\nabcd u'current_count': u'2', u'total_count': u'3', u'order_id': u'90'" |
sed -nr "s/.*('current_count': u'[0-9]+').*/\1/p"
# output: 'current_count': u'2'
Notice that I skip the grep by using sed -n s///p. I could also have used /current_count/ as an address:
sed -r -e '/current_count/!d' -e "s/.*('current_count': u'[0-9]+').*/\1/"
Or with just grep printing only the matching part of the pattern, instead of the whole line:
grep -E -o "'current_count': u'[[:digit:]]+'
(or egrep instead of grep -E). I forget if grep -o is POSIX-required behaviour.
For me this looks like some sort of serialized Python data. Basically I would try to find out the origin of that data and parse it properly.
However, while being hackish, sed can also being used here:
sed "s/.*current_count': [a-z]'\([0-9]\+\).*/\1/" input.txt
sed "s/.*total_count': [a-z]'\([0-9]\+\).*/\1/" input.txt

Removing text between "|" delimiter and "," delimiter using shell script

I have a large multi-lined file that is being pulled from a database the file has fields delimited by commas and if the field has multiple values the values are separated by "|"
example input:
name,title,email1|email2|email3,phone,address
In a shell script I need to remove "|email2|email3"
example output:
name,title,email1,phone,address
I need to do this for each line in the file.
Try sed:
sed "s/\|[^,]*//g"
Result:
h2co3-macbook:~ h2co3$ echo "name,title,email1|email2|email3,phone,address" | sed "s/\|[^,]*//g"
name,title,email1,phone,address
h2co3-macbook:~ h2co3$
Using sed:
sed -i 's/|[^,]*//g' filename
Note that in most regex flavors | is a special character that specifies alternation, and to match a literal | you need to use \|. This is not the case for sed, to match a literal | you use | and for alternation you use \| (unless an extended regex option is specified).
Use sed with inline option:
sed -i.bak 's/|[^|,]*//g' inFile
Live Demo: http://ideone.com/zKUVhl
This answer splits the input into fields and outputs the ones you want.
awk -F'[|,]' -v OFS=, '{print $1, $2, $3, $(NF-1), $NF}' file