as title said, Im trying to change only the first occurrence of word.By using
sed 's/this/that/' file.txt
though i'm not using g option it replace entire file. How to fix this.?
UPDATE:
$ cat file.txt
first line
this
this
this
this
$ sed -e '1s/this/that/;t' file.txt
first line
this // ------> I want to change only this "this" to "that" :)
this
this
this
http://www.faqs.org/faqs/editor-faq/sed/
4.3. How do I change only the first occurrence of a pattern?
sed -e '1s/LHS/RHS/;t' -e '1,/LHS/s//RHS/'
Where LHS=this and RHS=that for your example.
If you know the pattern won't occur on the first line, omit the first -e and the statement following it.
sed by itself applies the edit thru out the file and combined with "g" flag the edit is applied to all the occurrences on the same line.
e.g.
$ cat file.txt
first line
this this
this
this
this
$ sed 's/this/that/' file.txt
first line
that this
that
that
that
$ sed 's/this/that/g' file.txt
first line
that that <-- Both occurrences of "this" have changed
that
that
that
Related
how to remove comment lines (as # bal bla ) and empty lines (lines without charecters) from file with one sed command?
THX
lidia
If you're worried about starting two sed processes in a pipeline for performance reasons, you probably shouldn't be, it's still very efficient. But based on your comment that you want to do in-place editing, you can still do that with distinct commands (sed commands rather than invocations of sed itself).
You can either use multiple -e arguments or separate commands with a semicolon, something like (just one of these, not both):
sed -i 's/#.*$//' -e '/^$/d' fileName
sed -i 's/#.*$//;/^$/d' fileName
The following transcript shows this in action:
pax> printf 'Line # with a comment\n\n# Line with only a comment\n' >file
pax> cat file
Line # with a comment
# Line with only a comment
pax> cp file filex ; sed -i 's/#.*$//;/^$/d' filex ; cat filex
Line
pax> cp file filex ; sed -i -e 's/#.*$//' -e '/^$/d' filex ; cat filex
Line
Note how the file is modified in-place even with two -e options. You can see that both commands are executed on each line. The line with a comment first has the comment removed then all is removed because it's empty.
In addition, the original empty line is also removed.
#paxdiablo has a good answer but it can be improved.
(1) The '/^$/d' clause only matches 100% blank lines.
If you want to also match lines that are entirely whitespace (spaces, tabs etc.) use this instead:
'/^\s*$/d'
(2) The 's/#.*$//' clause only matches lines that start with the # character in column 0.
If you want to also match lines that have only whitespace before the first # use this instead:
'/^\s*#.*$/d'
The above criteria may not be universal (e.g. within a HEREDOC block, or in a Python multi-line string the different approaches could be significant), but in many cases the conventional definition of "blank" lines include whitespace-only, and "comment" lines include whitespace-then-#.
(3) Lastly, on OSX at least, the #paxdiablo solution in which the first clause turns comment lines into blank lines, and the second clause strips blank lines (including what were originally comments) doesn't work. It seems to be more portable to make both clauses /d delete actions as I've done.
The revised command incorporating the above is:
sed -e '/^\s*#.*$/d' -e '/^\s*$/d' inputFile
This tiny jewel removes all # comments, no matter where they begin in a line (see caution below):
sed -e 's/\s*#.*$//'
Example:
text="
this is a # test
#this is a test
#this is a #test
this is # another #test
"
$echo "$text" | sed -e 's/\s*#.*$//'
this is a
this is
Next this removes any resulting blank lines:
$echo "$text" | sed -e 's/\s*#.*$//' | sed -e '/^\s*$/d'
Caution: Depending on the syntax and/or interpretation of the lines your processing, this might not be an appropriate solution, as it just stupidly removes end of lines, even if the '#' is part of your data or code. However, for use cases where you'll never use a hash except for as an end of line comment then it works fine. So just as with all coding, context must be taken into consideration.
Alternative variant, using grep:
cat file.txt | grep -Ev '(#.*$)|(^$)'
you can use awk
awk 'NF{gsub(/^[ \t]*#/,"");print}' file
First example(paxdiablo) is very good except its not change file, just output result. If you want to change it inline:
sudo sed -i 's/#.*$//;/^$/d' inputFile
On (one of) my linux boxes, sed understands extended regular expressions with the -r option, so:
sed -r '/(^\s*#)|(^\s*$)/d' squid.conf.installed
is very useful for showing all non-blank, non comment lines.
The regex matches either start of line followed by zero or more spaces or tabs followed by either a hash or end of line, and deletes those matching lines from the input.
I have a file, which has multiple lines.
For example:
a
ab#
ad.
a12fs
b
c
...
I want to use sed or awk delete the line, if the line include symbols or numbers. (For example, I want to delete: ab#, ad., a12fs.... lines)
or in another words, I just want to keep the line which include [a-z][A-Z] .
I know how to delete number line,
sed '/[0-9]/d' file.txt
but I do not know how to delete symbols lines.
Or there has any easy way to do that?
To keep blank lines:
grep '^[[:alpha:]]*$' file
sed '/[^[:alpha:]]/d' file
awk '/^[[:alpha:]]*$/' file
To remove blank lines:
grep '^[[:alpha:]]+$' file
sed -E -n '/^[[:alpha:]]+$/p' file
awk '/^[[:alpha:]]+$/' file
grep works well too and is even simpler: just do the reverse: keep the lines that interest you, which are way easier to define
grep -i '^[a-z]*$' file.txt
(match lines containing only letters and empty lines, and -i option makes grep case-insensitive)
to remove empty lines as well:
grep -i '^[a-z]+$' file.txt
caution when using Windows text files, as there's a carriage return at the end of the line, so nothing would match depending on grep versions (tested on windows here and it works)
but just in case:
grep -iP '^[a-z]*\r?$'
(note the P option to enable perl expressions or \r is not recognized)
You can use this sed:
sed '/^[A-Za-z0-9]\+$/!d' file
(OR)
sed '/[^A-Za-z0-9]/d' file
$ awk '!/[^[:alpha:]]/' file.txt
a
b
c
I need to replace the whole line with sed if it matches a pattern.
For example if the line is 'one two six three four' and if 'six' is there, then the whole line should be replaced with 'fault'.
You can do it with either of these:
sed 's/.*six.*/fault/' file # check all lines
sed '/six/s/.*/fault/' file # matched lines -> then remove
It gets the full line containing six and replaces it with fault.
Example:
$ cat file
six
asdf
one two six
one isix
boo
$ sed 's/.*six.*/fault/' file
fault
asdf
fault
fault
boo
It is based on this solution to Replace whole line containing a string using Sed
More generally, you can use an expression sed '/match/s/.*/replacement/' file. This will perform the sed 's/match/replacement/' expression in those lines containing match. In your case this would be:
sed '/six/s/.*/fault/' file
What if we have 'one two six eight eleven three four' and we want to
include 'eight' and 'eleven' as our "bad" words?
In this case we can use the -e for multiple conditions:
sed -e 's/.*six.*/fault/' -e 's/.*eight.*/fault/' file
and so on.
Or also:
sed '/eight/s/.*/XXXXX/; /eleven/s/.*/XXXX/' file
Above answers worked fine for me, just mentioning an alternate way
Match single pattern and replace with a new one:
sed -i '/six/c fault' file
Match multiple pattern and replace with a new one(concatenating commands):
sed -i -e '/one/c fault' -e '/six/c fault' file
To replace whole line containing a specified string with the content of that line
Text file:
Row: 0 last_time_contacted=0, display_name=Mozart, _id=100, phonebook_bucket_alt=2
Row: 1 last_time_contacted=0, display_name=Bach, _id=101, phonebook_bucket_alt=2
Single string:
$ sed 's/.* display_name=\([[:alpha:]]\+\).*/\1/'
output:
100
101
Multiple strings delimited by white-space:
$ sed 's/.* display_name=\([[:alpha:]]\+\).* _id=\([[:digit:]]\+\).*/\1 \2/'
output:
Mozart 100
Bach 101
Adjust regex to meet your needs
[:alpha] and [:digit:]
are Character Classes and Bracket Expressions
This might work for you (GNU sed):
sed -e '/six/{c\fault' -e ';d}' file
or:
sed '/six/{c\fault'$'\n'';d}' file
All of the lines with comments in a file begin with #. How can I delete all of the lines (and only those lines) which begin with #? Other lines containing #, but not at the beginning of the line should be ignored.
This can be done with a sed one-liner:
sed '/^#/d'
This says, "find all lines that start with # and delete them, leaving everything else."
I'm a little surprised nobody has suggested the most obvious solution:
grep -v '^#' filename
This solves the problem as stated.
But note that a common convention is for everything from a # to the end of a line to be treated as a comment:
sed 's/#.*$//' filename
though that treats, for example, a # character within a string literal as the beginning of a comment (which may or may not be relevant for your case) (and it leaves empty lines).
A line starting with arbitrary whitespace followed by # might also be treated as a comment:
grep -v '^ *#' filename
if whitespace is only spaces, or
grep -v '^[ ]#' filename
where the two spaces are actually a space followed by a literal tab character (type "control-v tab").
For all these commands, omit the filename argument to read from standard input (e.g., as part of a pipe).
The opposite of Raymond's solution:
sed -n '/^#/!p'
"don't print anything, except for lines that DON'T start with #"
you can directly edit your file with
sed -i '/^#/ d'
If you want also delete comment lines that start with some whitespace use
sed -i '/^\s*#/ d'
Usually, you want to keep the first line of your script, if it is a sha-bang, so sed should not delete lines starting with #!. also it should delete lines, that just contain only a hash but no text. put it all together:
sed -i '/^\s*\(#[^!].*\|#$\)/d'
To be conform with all sed variants you need to add a backup extension to the -i option:
sed -i.bak '/^\s*#/ d' $file
rm -Rf $file.bak
You can use the following for an awk solution -
awk '/^#/ {sub(/#.*/,"");getline;}1' inputfile
This answer builds upon the earlier answer by Keith.
egrep -v "^[[:blank:]]*#" should filter out comment lines.
egrep -v "^[[:blank:]]*(#|$)" should filter out both comments and empty lines, as is frequently useful.
For information about [:blank:] and other character classes, refer to https://en.wikipedia.org/wiki/Regular_expression#Character_classes.
If you want to delete from the file starting with a specific word, then do this:
grep -v '^pattern' currentFileName > newFileName && mv newFileName currentFileName
So we have removed all the lines starting with a pattern, writing the content into a new file, and then copy the content back into the source/current file.
You also might want to remove empty lines as well
sed -E '/(^$|^#)/d' inputfile
Delete all empty lines and also all lines starting with a # after any spaces:
sed -E '/^$|^\s*#/d' inputfile
For example, see the following 3 deleted lines (including just line numbers!):
1. # first comment
2.
3. # second comment
After testing the command above, you can use option -i to edit the input file in place.
Just this!
Here is it with a loop for all files with some extension:
ll -ltr *.filename_extension > list.lst
for i in $(cat list.lst | awk '{ print $8 }') # validate if it is the 8 column on ls
do
echo $i
sed -i '/^#/d' $i
done
I need to delete the same line in a large number of text files. I have been trying to use sed, but I cannot get it to delete the newline character at the end. The following successfully deletes the line, but not the newline:
sed -i -e 's/VERSION:1//' *.txt
I have tried using the following to delete the newline also, but it does not work:
sed -i -e 's/VERSION:1\n//' *.txt
Is there anyway to specify a newline in a sed substitute command OR is there any other command line tool I can use to achieve my goal? Thank you
You can use the sed command:
sed -i -e '/VERSION:1/d'
for this.
The following transcript gives an example:
pax> echo 'hello
> goodbye
> hello again' | sed '/oo/d'
hello
hello again
You should also check whether you want to match whole lines with, for example:
sed -i -e '/^VERSION:1$/d'
since, as it stands, that will also delete lines like the following:
VERSION:10
CONVERSION:1
sed '/VERSION:1/{:q;N;s/VERSION\n//g;t q}' file