I have file in home/files/file.txt
and its contents mixed with letter and numbers
SDA212
123DD2
31dD
I want to copy file into other directory and at the same time replace numeric values with just X letter? I there any way that how I can do this?
Sounds like a job for sed.
sed -e 's/[0-9]/X/g' /home/files/file.txt > /path/somewhere/else.txt
Result:
SDAXXX
XXXDDX
XXdD
Edit: As #Ted Lyngmo pointed out, depending on your version of sed, you may be able to use the \d escape for digits:
sed -e 's/\d/X/g' /home/files/file.txt > /path/somewhere/else.txt
Just be aware that this is a gnu extension and may not be available on all systems.
You could use the tr program. I think something like tr '[:digit:]' X would work.
Related
I have an input stream of many lines which look like this:
path/to/file: example: 'extract_me.proto'
path/to/other-file: example: 'me_too.proto'
path/to/something/else: example: 'and_me_2.proto'
...
I'd like to just extract the *.proto filenames from these lines, and I have tried:
[INPUT] | sed 's/^.*\([a-zA-Z0-9_]+\.proto\).*$/\1/'
I know that part of my problem is that .* is greedy and I'm going to get things like e.proto and o.proto and 2.proto, but I can't even get that far... it just outputs with the same lines as the input. Any help would be greatly appreciated.
I find it helpful to use extended regex for this purpose (-r) in which case you need not escape your brackets.
sed -r 's/^.*[^a-zA-Z0-9_]([a-zA-Z0-9_]+\.proto).*$/\1/'
The addition of [^a-zA-Z0-9_] forces the .* to not be greedy.
Since you tag your command with linux, I'll assume you have GNU grep. Pick one of
grep -oP '\w+\.proto' file
grep -o "[^']+\\.proto" file
one way to do it:
sed 's/^.*[^a-zA-Z0-9_]\([a-zA-Z0-9_]\+\.proto\).*$/\1/'
escaped the + char
put a negation before the alphanum+underscore to delimit the leading chars
another way: use single quote delimitation, after all it's here for that:
sed "s/^.*'\([a-zA-Z0-9_]\+\.proto\)'.*\$/\1/"
Use this sed:
sed "s/^.*'\([a-zA-Z0-9_]\+\.proto\).*$/\1/"
+ - Extended-RegEx. So, you need to escape to get special meaning. The preceding item will be matched one or more times.
Another way:
sed "s/^.*'\([^']\+\.proto\)'.*$/\1/"
With GNU sed:
sed -E "s/.*'([^']+)'$/\1/"
My question is probably rather simple. I'm trying to replace sequences of strings that are at the beginning of lines in a file. For example, I would like to replace any instance of the pattern "GN" with "N" or "WR" with "R", but only if they are the first 2 characters of that line. For example, if I had a file with the following content:
WRONG
RIGHT
GNOME
I would like to transform this file to give
RONG
RIGHT
NOME
I know i can use the following to replace any instance of the above example;
sed -i 's/GN/N/g' file.txt
sed -i 's/WR/R/g' file.txt
The issue is that I want this to happen only if the above patterns are the first 2 characters in any given line. Possibly an IF statement, although i'm not sure what the condition would look like. Any pointers in the right direction would be much appreciated, thanks.
just add the circumflex, remove g suffix (unnecessary, since you want at most one replacement), you can also combine them in one script.
sed -i 's/^GN/N/;s/^WR/R/' file.txt
Use the start-of-string regexp anchor ^:
sed -i 's/^GN/N/' file.txt
sed -i 's/^WR/R/' file.txt
Since sed is line-oriented, start-of-string == start-of-line.
I need to replace within a little bash script a string inside a file but... I am getting weird results.
Let's say I want to replace:
<tag><![CDATA[text]]></tag>
With:
<tag><![CDATA[replaced_text]]></tag>
Should I use sed? I think due to / and [ ] I am getting weird results...
What would be the best way of approaching this?
Perl with -p option works almost as sed and it has \Q (quote) switch for its regexes:
perl -pe 's{\Q<tag><![CDATA[text]]></tag>}
{<tag><![CDATA[replaced_text]]></tag>}' YOUR_FILE
And in Perl you can use different punctuation to delimiter your expressions (s{...}{...} in my example).
Yes, you need to escape the brackets, and either escape slashes or use different delimiters.
sed 's,<tag><!\[CDATA\[text\]\]></tag>,<tag><!\[CDATA\[replaced)text\]\]></tag>,'
That said, SGML and XML are not actually any better than HTML when it comes to using regexes; don't expect this to generalize.
This should be enough:
$ echo '<tag><![CDATA[text]]></tag>' | sed 's/\[text\]/\[replaced_text\]/'
<tag><![CDATA[replaced_text]]></tag>
You can also change your / separator inside sed to a different character like ,, | or %.
Just use a delimiter other than /, here I use #:
sed -i 's#<tag><!\[CDATA\[text\]\]></tag>#<tag><![CDATA[replaced_text]]></tag>#g' filename
-i to have sed change the file instead of printing it out.
g is for matching more than once (global).
But do you know the exact string you want to match, both the tag and the text?
For instance, if you want to replace the text in all with your replaced_text:
perl -i -pe 's#(<tag><!\[CDATA\[)(.*?)(\]\]></tag>)#\1replaced_text\3#g' filename
Switched to perl because sed doesn't support non-greedy multipliers (the *?).
I wish to process files (.krn-files that can be read as txtfiles) and replace every occurence of { with x . Is it possible to do this on the command-line?
As I wish to do this in many files, my idea is to be able to go through all the files in a folder and process them one and one. How can this be achieved? I understand that grep may come in handy...
You can use sed:
sed -i 's/{/x/g' *
sed is the wrong tool for this job, but if you are going to use sed, do it with y instead of s
sed 'y/{/x/'
The correct tool for translating characters is tr
tr { x
If you opened the filem then use this below command...
:%s/{/x/
I have a set of 10 CSV files, which normally have a an entry of this kind
a,b,c,d
d,e,f,g
Now due to some error entries in this file have become of this kind
a,b,c,d
d,e,f,g
,,,
h,i,j,k
Now I want to remove the line with only commas in all the files. These files are on a Linux filesystem.
Any command that you recommend that can replaces the erroneous lines in all the files.
It depends on what you mean by replace. If you mean 'remove', then a trivial variant on #wnoise's solution is:
grep -v '^,,,$' old-file.csv > new-file.csv
Note that this deletes just those lines with exactly three commas. If you want to delete mal-formed lines with any number of commas (including zero) - and no other characters on the line, then:
grep -v '^,*$' ...
There are endless other variations on the regex that would deal with other scenarios. Dealing with full CSV data with commas inside quotes starts to need something other than a regex machine. It can be done, within broad limits, especially in more complex regex systems such as PCRE or Perl. But it requires more work.
Check out Mastering Regular Expressions.
sed 's/,,,/replacement/' < old-file.csv > new-file.csv
optionally followed by
mv new-file.csv old-file.csv
Replace or remove, your post is not clear... For replacement see wnoise's answer. For removing, you could use
awk '$0 !~ /,,,/ {print}' <old-file.csv > new-file.csv
What about trying to keep only lines which are matching the desired format instead of handling one exception ?
If the provided input is what you really want to match:
grep -E '[a-z],[a-z],[a-z],[a-z]' < oldfile.csv > newfile.csv
If the input is different, provide it, the regular expression should not be too hard to write.
Do you want to replace them with something, or delete them entirely? Either way, it can be done with sed. To delete:
sed -i -e '/^,\+$/ D' yourfile1.csv yourfile2.csv ...
To replace: well, see wnoise's answer, or if you don't want to create new files with the output,
sed -i -e '/^,\+$/ s//replacement/' yourfile1.csv yourfile2.csv ...
or
sed -i -e '/^,\+$/ c\
replacement' yourfile1.csv yourfile2.csv ...
(that should be entered exactly as is, including the line break). Of course, you can also do this with awk or perl or, if you're only deleting lines, even grep:
egrep -v '^,+$' < oldfile.csv > newfile.csv
I tested these to make sure they work, but I'd advise you to do the same before using them (just in case). You can omit the -i option from sed, in which case it'll print out the results (rather than writing them back to the file), or omit the output redirection >newfile.csv from grep.
EDIT: It was pointed out in a comment that some features of these sed commands only work on GNU sed. As far as I can tell, these are the -i option (which can be replaced with shell redirection, sed ... <infile >outfile ) and the \+ modifier (which can be replaced with \{1,\} ).
Most simply:
$ grep -v ,,,, oldfile > newfile
$ mv newfile oldfile
yes, awk or grep are very good option if you are working in linux platform. However you can use perl regex for other platform. using join & split options.