I am trying to find alphanumeric string including these two characters "/+" with at least 30 characters in length.
I have written this code,
grep "[a-zA-Z0-9\/\+]{30,}" tmp.txt
cat tmp.txt
> array('rWmyiJgKT8sFXCmMr639U4nWxcSvVFEur9hNOOvQwF/tpYRqTk9yWV2xPFBAZwAPRVs/s
ddd73ZEjfy+airfy8DtqIqKI9+dd 6hdd7soJ9iG0sGs/ld5f2GHzockoYHfh
+pAzx/t17Crf0T/2+8+reo+MU39lqCr02sAkcC1k/LzyBvSDEtu9N/9NHicr jA3SvDqg5s44DFlaNZ/8BW37fGEf2rk13S/q68OVVyzac7IT7yE7PIL9XZ/6LsmrY
KEsAmN4i/+ym8be3wwn KWGYaIB908+7W98pI6qao3iaZB
3mh7Y/nZm52hyLa37978f+PyOCqUh0Wfx2PL3vglofi0l
QVrOM1pg+mFLEIC88B706UzL4Pss7ouEo+EsrES+/qJq9Y1e/UGvwefOWSL2TJdt
this does not work, Mainly I wanted to have minimum length of the string to be 30
In the syntax of grep, the repetition braces need to be backslashed.
grep -o '[a-zA-Z0-9/+]\{30,\}' file
If you want to constrain the match to lines containing only matches to this pattern, add line-start and line-ending anchors:
grep '^[a-zA-Z0-9/+]\{30,\}$' file
The -o option in the first command line causes grep to only print the matching part, not the entire matching line.
The repetition operator is not directly supported in Basic Regular Expression syntax. Use grep -E to enable Extended Regular Expression syntax, or backslash the braces.
You can use
grep -e "^[a-zA-Z0-9/+]\{30,\}" tmp.txt
grep -e "^[a-zA-Z0-9/+]\{30,\}" tmp.txt
+pAzx/t17Crf0T/2+8+reo+MU39lqCr02sAkcC1k/LzyBvSDEtu9N/9NHicr jA3SvDqg5s44DFlaNZ/8BW37fGEf2rk13S/q68OVVyzac7IT7yE7PIL9XZ/6LsmrY
3mh7Y/nZm52hyLa37978f+PyOCqUh0Wfx2PL3vglofi0l
QVrOM1pg+mFLEIC88B706UzL4Pss7ouEo+EsrES+/qJq9Y1e/UGvwefOWSL2TJdt
man grep
Read up about the difference between between regular and extended patterns. You need the -E option.
Related
Is there a way to make grep output "words" from files that match the search expression?
If I want to find all the instances of, say, "th" in a number of files, I can do:
grep "th" *
but the output will be something like (bold is by me);
some-text-file : the cat sat on the mat
some-other-text-file : the quick brown fox
yet-another-text-file : i hope this explains it thoroughly
What I want it to output, using the same search, is:
the
the
the
this
thoroughly
Is this possible using grep? Or using another combination of tools?
Try grep -o:
grep -oh "\w*th\w*" *
Edit: matching from Phil's comment.
From the docs:
-h, --no-filename
Suppress the prefixing of file names on output. This is the default
when there is only one file (or only standard input) to search.
-o, --only-matching
Print only the matched (non-empty) parts of a matching line,
with each such part on a separate output line.
Cross distribution safe answer (including windows minGW?)
grep -h "[[:alpha:]]*th[[:alpha:]]*" 'filename' | tr ' ' '\n' | grep -h "[[:alpha:]]*th[[:alpha:]]*"
If you're using older versions of grep (like 2.4.2) which do not include the -o option, then use the above. Else use the simpler to maintain version below.
Linux cross distribution safe answer
grep -oh "[[:alpha:]]*th[[:alpha:]]*" 'filename'
To summarize: -oh outputs the regular expression matches to the file content (and not its filename), just like how you would expect a regular expression to work in vim/etc... What word or regular expression you would be searching for then, is up to you! As long as you remain with POSIX and not perl syntax (refer below)
More from the manual for grep
-o Print each match, but only the match, not the entire line.
-h Never print filename headers (i.e. filenames) with output lines.
-w The expression is searched for as a word (as if surrounded by
`[[:<:]]' and `[[:>:]]';
The reason why the original answer does not work for everyone
The usage of \w varies from platform to platform, as it's an extended "perl" syntax. As such, those grep installations that are limited to work with POSIX character classes use [[:alpha:]] and not its perl equivalent of \w. See the Wikipedia page on regular expression for more
Ultimately, the POSIX answer above will be a lot more reliable regardless of platform (being the original) for grep
As for support of grep without -o option, the first grep outputs the relevant lines, the tr splits the spaces to new lines, the final grep filters only for the respective lines.
(PS: I know most platforms by now would have been patched for \w.... but there are always those that lag behind)
Credit for the "-o" workaround from #AdamRosenfield answer
It's more simple than you think. Try this:
egrep -wo 'th.[a-z]*' filename.txt #### (Case Sensitive)
egrep -iwo 'th.[a-z]*' filename.txt ### (Case Insensitive)
Where,
egrep: Grep will work with extended regular expression.
w : Matches only word/words instead of substring.
o : Display only matched pattern instead of whole line.
i : If u want to ignore case sensitivity.
You could translate spaces to newlines and then grep, e.g.:
cat * | tr ' ' '\n' | grep th
Just awk, no need combination of tools.
# awk '{for(i=1;i<=NF;i++){if($i~/^th/){print $i}}}' file
the
the
the
this
thoroughly
grep command for only matching and perl
grep -o -P 'th.*? ' filename
I was unsatisfied with awk's hard to remember syntax but I liked the idea of using one utility to do this.
It seems like ack (or ack-grep if you use Ubuntu) can do this easily:
# ack-grep -ho "\bth.*?\b" *
the
the
the
this
thoroughly
If you omit the -h flag you get:
# ack-grep -o "\bth.*?\b" *
some-other-text-file
1:the
some-text-file
1:the
the
yet-another-text-file
1:this
thoroughly
As a bonus, you can use the --output flag to do this for more complex searches with just about the easiest syntax I've found:
# echo "bug: 1, id: 5, time: 12/27/2010" > test-file
# ack-grep -ho "bug: (\d*), id: (\d*), time: (.*)" --output '$1, $2, $3' test-file
1, 5, 12/27/2010
cat *-text-file | grep -Eio "th[a-z]+"
You can also try pcregrep. There is also a -w option in grep, but in some cases it doesn't work as expected.
From Wikipedia:
cat fruitlist.txt
apple
apples
pineapple
apple-
apple-fruit
fruit-apple
grep -w apple fruitlist.txt
apple
apple-
apple-fruit
fruit-apple
I had a similar problem, looking for grep/pattern regex and the "matched pattern found" as output.
At the end I used egrep (same regex on grep -e or -G didn't give me the same result of egrep) with the option -o
so, I think that could be something similar to (I'm NOT a regex Master) :
egrep -o "the*|this{1}|thoroughly{1}" filename
To search all the words with start with "icon-" the following command works perfect. I am using Ack here which is similar to grep but with better options and nice formatting.
ack -oh --type=html "\w*icon-\w*" | sort | uniq
You could pipe your grep output into Perl like this:
grep "th" * | perl -n -e'while(/(\w*th\w*)/g) {print "$1\n"}'
grep --color -o -E "Begin.{0,}?End" file.txt
? - Match as few as possible until the End
Tested on macos terminal
$ grep -w
Excerpt from grep man page:
-w: Select only those lines containing matches that form whole words. The test is that the matching substring must either be at the beginning of the line, or preceded by a non-word constituent character.
ripgrep
Here are the example using ripgrep:
rg -o "(\w+)?th(\w+)?"
It'll match all words matching th.
iam trining to find the longest word in a text file.
i tried it and find out the no of characters in the longest word in a file
by using the command
wc -L
i need to print the longest word By using this number and grep command .
If you must use the two commands give, I'd suggest:
grep -E ".{$(wc -L < test.txt)}" test.txt
The command substitution is used to build the correct brace expression to match the line(s) with exactly the given number of characters. -E is needed to enable extended regular expression support; otherwise, the braces need to be escaped: grep ".\{...\}" test.txt.
Using an awk command that makes a single pass through the file may be faster.
Is there a way to grep (or use another command) to find exact strings, using NO regex?
For example, if I want to search for (literally):
/some/file"that/has'lots\of"invalid"chars/and.triggers$(#2)[*~.old][3].html
I don't want to go through and escape every single "escapable". Essentially, I want to pass it through, like I would with echo:
$ echo "/some/file\"that/has'lots\of\"invalid\"chars/and.triggers$(#2)[*~.old][3].html"
/some/file"that/has'lots\of"invalid"chars/and.triggers$(#2)[*~.old][3].html
Use fgrep, it's the same as grep -F (matches a fixed string).
Well, you can put the information you want to match, each in a line, and then use grep:
grep -F -f patterns.txt file.txt
Notice the usage of the flag -F, which causes grep to consider each line of the file patterns.txt as a fixed-string to be searched in file.txt.
HI
I am not very good with linux shell scripting.I am trying following shell script to replace
revision number token $rev -<rev number> in all html files under specified directory
cd /home/myapp/test
set repUpRev = "`svnversion`"
echo $repUpRev
grep -lr -e '\$rev -'.$repUpRev.'\$' *.html | xargs sed -i 's/'\$rev -'.$repUpRev.'\$'/'\$rev -.*$'/g'
This seems not working, what is wrong with the above code ?
rev=$(svnversion)
sed -i.bak "s/$rev/some other string/g" *.html
What is $rev in the regexp string? Is it another variable? Or you're looking for a string '$rev'. If latter - I would suggest adding '\' before $ otherwise it's treated as a special regexp character...
This is how you show the last line:
grep -lr -e '\$rev -'.$repUpRev.'\$' *.html | xargs sed -i 's/'\$rev -'.$repUpRev.'\$'/'\$rev -.*$'/g'
It would help if you showed some input data.
The -r option makes the grep recursive. That means it will operate on files in the directory and its subdirectories. Is that what you intend?
The dots in your grep and sed stand for any character. If you want literal dots, you'll need to escape them.
The final escaped dollar sign in the grep and sed commands will be seen as a literal dollar sign. If you want to anchor to the end of the line you should remove the escape.
The .* works only as a literal string on the right hand side of a sed s command. If you want to include what was matched on the left side, you need to use capture groups. The g modifier on the s command is only needed if the pattern appears more than once in a line.
Using quote, unquote, quote, unquote is hard to read. Use double quotes to permit variable expansion.
Try your grep command by itself without the xargs and sed to see if it's producing a list of files.
This may be closer to what you want:
grep -lr -e "\$rev -.$repUpRev.$" *.html | xargs sed -i "s/\$rev -.$repUpRev.$/\$rev -REPLACEMENT_TEXT/g"
but you'll still need to determine if the g modifier, the dots, the final dollar signs, etc., are what you intend.
I needed to find all the files that contained a specific string pattern. The first solution that comes to mind is using find piped with xargs grep:
find . -iname '*.py' | xargs grep -e 'YOUR_PATTERN'
But if I need to find patterns that spans on more than one line, I'm stuck because vanilla grep can't find multiline patterns.
Why don't you go for awk:
awk '/Start pattern/,/End pattern/' filename
Here is the example using GNU grep:
grep -Pzo '_name.*\n.*_description'
-z/--null-data Treat the input as a set of lines, each terminated by a zero byte (the ASCII NUL character) instead of a newline.
Which has the effect of treating the whole file as one large line.
See -z description on grep's manual and also common question no 14 on grep's manual usage page
So I discovered pcregrep which stands for Perl Compatible Regular Expressions GREP.
the -M option makes it possible to search for patterns that span line boundaries.
For example, you need to find files where the '_name' variable is followed on the next line by the '_description' variable:
find . -iname '*.py' | xargs pcregrep -M '_name.*\n.*_description'
Tip: you need to include the line break character in your pattern. Depending on your platform, it could be '\n', \r', '\r\n', ...
grep -P also uses libpcre, but is much more widely installed. To find a complete title section of an html document, even if it spans multiple lines, you can use this:
grep -P '(?s)<title>.*</title>' example.html
Since the PCRE project implements to the perl standard, use the perl documentation for reference:
http://perldoc.perl.org/perlre.html#Modifiers
http://perldoc.perl.org/perlre.html#Extended-Patterns
Here is a more useful example:
pcregrep -Mi "<title>(.*\n){0,5}</title>" afile.html
It searches the title tag in a html file even if it spans up to 5 lines.
Here is an example of unlimited lines:
pcregrep -Mi "(?s)<title>.*</title>" example.html
With silver searcher:
ag 'abc.*(\n|.)*efg'
Speed optimizations of silver searcher could possibly shine here.
#Marcin:
awk example non-greedy:
awk '{if ($0 ~ /Start pattern/) {triggered=1;}if (triggered) {print; if ($0 ~ /End pattern/) { exit;}}}' filename
You can use the grep alternative sift here (disclaimer: I am the author).
It support multiline matching and limiting the search to specific file types out of the box:
sift -m --files '*.py' 'YOUR_PATTERN'
(search all *.py files for the specified multiline regex pattern)
It is available for all major operating systems. Take a look at the samples page to see how it can be used to to extract multiline values from an XML file.
This answer might be useful:
Regex (grep) for multi-line search needed
To find recursively you can use flags -R (recursive) and --include (GLOB pattern). See:
Use grep --exclude/--include syntax to not grep through certain files
perl -ne 'print if (/begin pattern/../end pattern/)' filename
Using ex/vi editor and globstar option (syntax similar to awk and sed):
ex +"/string1/,/string3/p" -R -scq! file.txt
where aaa is your starting point, and bbb is your ending text.
To search recursively, try:
ex +"/aaa/,/bbb/p" -scq! **/*.py
Note: To enable ** syntax, run shopt -s globstar (Bash 4 or zsh).