I have a file.xml so composed:
...some xml text here...
<Version>1.0.13-alpha</Version>
...some xml text here...
I need to extract the following information:
mayor_and_minor_release_number --> 1.0
patch_number --> 13
suffix --> -alpha
I've thought the cleanest way to achieve that is by mean of a regex with grep command:
<Version>(\d+\.\d+)\.(\d+)([\w-]+)?<\/Version>
I've checked with regex101 the correctness of this regex and actually it seems to properly capture the 3 fields I'm looking for. But here comes the problem, since I have no idea how to print those fields.
cat file.xml | grep "<Version>(\d+\.\d+)\.(\d+)([\w-]+)?<\/Version>" -oP
This command prints the entire line so it's quite useless.
Several posts on this site have been written about this topic, so I've also tried to use the bash native
regex support, with poor results:
regex="<Version>(\d+\.\d+)\.(\d+)([\w-]+)?<\/Version>"
txt=$(cat file.xml)
[[ "$txt" =~ $regex ]] --> it fails!
echo "${BASH_REMATCH[*]}"
I'm sorry but I cannot figure out how to overtake this issue. The desired output should be:
1.0
13
-alpha
You may use this read + sed solution with similar regex as your's:
read -r major minor suffix < <(
sed -nE 's~.*<Version>([0-9]+\.[0-9]+)\.([0-9]+)(-[^<]*)</Version>.*~\1 \2 \3~p' file.xml
)
Check variable contents:
declare -p major minor suffix
declare -- major="1.0"
declare -- minor="13"
declare -- suffix="-alpha"
Few points:
You cannot use \d without using -P (perl) mode in grep
grep command doesn't return capture groups
Use this Perl one-liner:
perl -lne 'print for m{<Version>(\d+\.\d+)\.(\d+)([\w-]+)?<\/Version>};' file.xml
Example:
echo '<Version>1.0.13-alpha</Version>' | perl -lne 'print for m{<Version>(\d+\.\d+)\.(\d+)([\w-]+)?<\/Version>};'
Output:
1.0
13
-alpha
The Perl one-liner uses these command line flags:
-e : Tells Perl to look for code in-line, instead of in a file.
-n : Loop over the input one line at a time, assigning it to $_ by default.
-l : Strip the input line separator ("\n" on *NIX by default) before executing the code in-line, and append it when printing.
SEE ALSO:
perldoc perlrun: how to execute the Perl interpreter: command line switches
Given a file, for example:
potato: 1234
apple: 5678
potato: 5432
grape: 4567
banana: 5432
sushi: 56789
I'd like to grep for all lines that start with potato: but only pipe the numbers that follow potato:. So in the above example, the output would be:
1234
5432
How can I do that?
grep 'potato:' file.txt | sed 's/^.*: //'
grep looks for any line that contains the string potato:, then, for each of these lines, sed replaces (s/// - substitute) any character (.*) from the beginning of the line (^) until the last occurrence of the sequence : (colon followed by space) with the empty string (s/...// - substitute the first part with the second part, which is empty).
or
grep 'potato:' file.txt | cut -d\ -f2
For each line that contains potato:, cut will split the line into multiple fields delimited by space (-d\ - d = delimiter, \ = escaped space character, something like -d" " would have also worked) and print the second field of each such line (-f2).
or
grep 'potato:' file.txt | awk '{print $2}'
For each line that contains potato:, awk will print the second field (print $2) which is delimited by default by spaces.
or
grep 'potato:' file.txt | perl -e 'for(<>){s/^.*: //;print}'
All lines that contain potato: are sent to an inline (-e) Perl script that takes all lines from stdin, then, for each of these lines, does the same substitution as in the first example above, then prints it.
or
awk '{if(/potato:/) print $2}' < file.txt
The file is sent via stdin (< file.txt sends the contents of the file via stdin to the command on the left) to an awk script that, for each line that contains potato: (if(/potato:/) returns true if the regular expression /potato:/ matches the current line), prints the second field, as described above.
or
perl -e 'for(<>){/potato:/ && s/^.*: // && print}' < file.txt
The file is sent via stdin (< file.txt, see above) to a Perl script that works similarly to the one above, but this time it also makes sure each line contains the string potato: (/potato:/ is a regular expression that matches if the current line contains potato:, and, if it does (&&), then proceeds to apply the regular expression described above and prints the result).
Or use regex assertions: grep -oP '(?<=potato: ).*' file.txt
grep -Po 'potato:\s\K.*' file
-P to use Perl regular expression
-o to output only the match
\s to match the space after potato:
\K to omit the match
.* to match rest of the string(s)
sed -n 's/^potato:[[:space:]]*//p' file.txt
One can think of Grep as a restricted Sed, or of Sed as a generalized Grep. In this case, Sed is one good, lightweight tool that does what you want -- though, of course, there exist several other reasonable ways to do it, too.
This will print everything after each match, on that same line only:
perl -lne 'print $1 if /^potato:\s*(.*)/' file.txt
This will do the same, except it will also print all subsequent lines:
perl -lne 'if ($found){print} elsif (/^potato:\s*(.*)/){print $1; $found++}' file.txt
These command-line options are used:
-n loop around each line of the input file
-l removes newlines before processing, and adds them back in afterwards
-e execute the perl code
You can use grep, as the other answers state. But you don't need grep, awk, sed, perl, cut, or any external tool. You can do it with pure bash.
Try this (semicolons are there to allow you to put it all on one line):
$ while read line;
do
if [[ "${line%%:\ *}" == "potato" ]];
then
echo ${line##*:\ };
fi;
done< file.txt
## tells bash to delete the longest match of ": " in $line from the front.
$ while read line; do echo ${line##*:\ }; done< file.txt
1234
5678
5432
4567
5432
56789
or if you wanted the key rather than the value, %% tells bash to delete the longest match of ": " in $line from the end.
$ while read line; do echo ${line%%:\ *}; done< file.txt
potato
apple
potato
grape
banana
sushi
The substring to split on is ":\ " because the space character must be escaped with the backslash.
You can find more like these at the linux documentation project.
Modern BASH has support for regular expressions:
while read -r line; do
if [[ $line =~ ^potato:\ ([0-9]+) ]]; then
echo "${BASH_REMATCH[1]}"
fi
done
grep potato file | grep -o "[0-9].*"
I have a file that has a line stating
version = "12.0.08-SNAPSHOT"
The word version and quoted strings can occur on multiple lines in that file.
I am looking for a single line bash statement that can output the following string:
12.0.08-SNAPSHOT
The version can have RELEASE tag too instead of SNAPSHOT.
So to summarize, given
version = "12.0.08-SNAPSHOT"
expected output: 12.0.08-SNAPSHOT
And given
version = "12.0.08-RELEASE"
expected output: 12.0.08-RELEASE
The following command prints strings enquoted in version = "...":
grep -Po '\bversion\s*=\s*"\K.*?(?=")' yourFile
-P enables perl regexes, which allow us to use features like \K and so on.
-o only prints matched parts instead of the whole lines.
\b ensures that version starts at a word boundary and we do not match things like abcversion.
\s stands for any kind of whitespace.
\K lets grep forget, that it matched the part before \K. The forgotten part will not be printed.
.*? matches as few chararacters as possible (the matching part will be printed) ...
(?=") ... until we see a ", which won't be included in the match either (this is called a lookahead).
Not all grep implementations support the -P option. Alternatively, you can use perl, as described in this answer:
perl -nle 'print $& if m{\bversion\s*=\s*"\K.*?(?=")}' yourFile
Seems like a job for cut:
$ echo 'version = "12.0.08-SNAPSHOT"' | cut -d'"' -f2
12.0.08-SNAPSHOT
$ echo 'version = "12.0.08-RELEASE"' | cut -d'"' -f2
12.0.08-RELEASE
Portable solution:
$ echo 'version = "12.0.08-RELEASE"' |sed -E 's/.*"(.*)"/\1/g'
12.0.08-RELEASE
or even:
$ perl -pe 's/.*"(.*)"/\1/g'.
$ awk -F"\"" '{print $2}'
In bash, I have the following:
#!/bin/bash
curl $1 | tac | tac | perl -e '/(\d\d(?=:\d\d))/g; print $1' > $2
All I want is to the first match from the output of curl and print it to the output file. I run the script with ./scriptname url outputfile.txt but nothing is printed. My regex is valid on http://regexr.com, so I'm sure it's something I don't know about Perl. What am I doing wrong? Thanks.
You can use the following:
#!/bin/bash
curl "$1" | perl -nle'print for /\d\d(?=:\d\d)/g' > "$2"
If you change the match to /script/g, you can see it working with something like
./scriptname http://www.ucsd.edu outputfile.txt
I suppose this means perl -ne is reading the input line by line. Is there a simple way to have perl return only the first result?
Consider using sed:
... | sed '/^.*\([[:digit:]]\{2\}\):[[:digit:]]\{2\}.*/{s//\1/;q};d'
In Perl, that would be:
... | perl -nle 'if (s/^.*(\d\d):\d\d.*/$1/) { print; exit }'
And with GNU Grep compiled with --perl-regexp:
... | grep -m1 -Po '\d\d(?=:\d\d)'
There are a few problems:
You never read from STDIN.
You don't stop trying to match after the first match.
You print unconditionally.
If you want all matches (as per your original question):
perl -nle'print for /\d\d(?=:\d\d)/g'
If you want the first match (as per your comment):
perl -nle'if (/\d\d(?=:\d\d)/) { print $&; exit }'
perl -nle'if (/(\d\d):\d\d/) { print $1; exit }'
grep -Pom1 '\d\d(?=:\d\d)'
Notes:
-n wraps the code with a loop that reads from STDIN.
I am trying to use grep to match lines that contain two different strings. I have tried the following but this matches lines that contain either string1 or string2 which not what I want.
grep 'string1\|string2' filename
So how do I match with grep only the lines that contain both strings?
You can use
grep 'string1' filename | grep 'string2'
Or
grep 'string1.*string2\|string2.*string1' filename
I think this is what you were looking for:
grep -E "string1|string2" filename
I think that answers like this:
grep 'string1.*string2\|string2.*string1' filename
only match the case where both are present, not one or the other or both.
To search for files containing all the words in any order anywhere:
grep -ril \'action\' | xargs grep -il \'model\' | xargs grep -il \'view_type\'
The first grep kicks off a recursive search (r), ignoring case (i) and listing (printing out) the name of the files that are matching (l) for one term ('action' with the single quotes) occurring anywhere in the file.
The subsequent greps search for the other terms, retaining case insensitivity and listing out the matching files.
The final list of files that you will get will the ones that contain these terms, in any order anywhere in the file.
If you have a grep with a -P option for a limited perl regex, you can use
grep -P '(?=.*string1)(?=.*string2)'
which has the advantage of working with overlapping strings. It's somewhat more straightforward using perl as grep, because you can specify the and logic more directly:
perl -ne 'print if /string1/ && /string2/'
Your method was almost good, only missing the -w
grep -w 'string1\|string2' filename
You could try something like this:
(pattern1.*pattern2|pattern2.*pattern1)
The | operator in a regular expression means or. That is to say either string1 or string2 will match. You could do:
grep 'string1' filename | grep 'string2'
which will pipe the results from the first command into the second grep. That should give you only lines that match both.
And as people suggested perl and python, and convoluted shell scripts, here a simple awk approach:
awk '/string1/ && /string2/' filename
Having looked at the comments to the accepted answer: no, this doesn't do multi-line; but then that's also not what the author of the question asked for.
Don't try to use grep for this, use awk instead. To match 2 regexps R1 and R2 in grep you'd think it would be:
grep 'R1.*R2|R2.*R1'
while in awk it'd be:
awk '/R1/ && /R2/'
but what if R2 overlaps with or is a subset of R1? That grep command simply would not work while the awk command would. Lets say you want to find lines that contain the and heat:
$ echo 'theatre' | grep 'the.*heat|heat.*the'
$ echo 'theatre' | awk '/the/ && /heat/'
theatre
You'd have to use 2 greps and a pipe for that:
$ echo 'theatre' | grep 'the' | grep 'heat'
theatre
and of course if you had actually required them to be separate you can always write in awk the same regexp as you used in grep and there are alternative awk solutions that don't involve repeating the regexps in every possible sequence.
Putting that aside, what if you wanted to extend your solution to match 3 regexps R1, R2, and R3. In grep that'd be one of these poor choices:
grep 'R1.*R2.*R3|R1.*R3.*R2|R2.*R1.*R3|R2.*R3.*R1|R3.*R1.*R2|R3.*R2.*R1' file
grep R1 file | grep R2 | grep R3
while in awk it'd be the concise, obvious, simple, efficient:
awk '/R1/ && /R2/ && /R3/'
Now, what if you actually wanted to match literal strings S1 and S2 instead of regexps R1 and R2? You simply can't do that in one call to grep, you have to either write code to escape all RE metachars before calling grep:
S1=$(sed 's/[^^]/[&]/g; s/\^/\\^/g' <<< 'R1')
S2=$(sed 's/[^^]/[&]/g; s/\^/\\^/g' <<< 'R2')
grep 'S1.*S2|S2.*S1'
or again use 2 greps and a pipe:
grep -F 'S1' file | grep -F 'S2'
which again are poor choices whereas with awk you simply use a string operator instead of regexp operator:
awk 'index($0,S1) && index($0.S2)'
Now, what if you wanted to match 2 regexps in a paragraph rather than a line? Can't be done in grep, trivial in awk:
awk -v RS='' '/R1/ && /R2/'
How about across a whole file? Again can't be done in grep and trivial in awk (this time I'm using GNU awk for multi-char RS for conciseness but it's not much more code in any awk or you can pick a control-char you know won't be in the input for the RS to do the same):
awk -v RS='^$' '/R1/ && /R2/'
So - if you want to find multiple regexps or strings in a line or paragraph or file then don't use grep, use awk.
git grep
Here is the syntax using git grep with multiple patterns:
git grep --all-match --no-index -l -e string1 -e string2 -e string3 file
You may also combine patterns with Boolean expressions such as --and, --or and --not.
Check man git-grep for help.
--all-match When giving multiple pattern expressions, this flag is specified to limit the match to files that have lines to match all of them.
--no-index Search files in the current directory that is not managed by Git.
-l/--files-with-matches/--name-only Show only the names of files.
-e The next parameter is the pattern. Default is to use basic regexp.
Other params to consider:
--threads Number of grep worker threads to use.
-q/--quiet/--silent Do not output matched lines; exit with status 0 when there is a match.
To change the pattern type, you may also use -G/--basic-regexp (default), -F/--fixed-strings, -E/--extended-regexp, -P/--perl-regexp, -f file, and other.
Related:
How to grep for two words existing on the same line?
Check if all of multiple strings or regexes exist in a file
How to run grep with multiple AND patterns? & Match all patterns from file at once
For OR operation, see:
How do I grep for multiple patterns with pattern having a pipe character?
Grep: how to add an “OR” condition?
Found lines that only starts with 6 spaces and finished with:
cat my_file.txt | grep
-e '^ .*(\.c$|\.cpp$|\.h$|\.log$|\.out$)' # .c or .cpp or .h or .log or .out
-e '^ .*[0-9]\{5,9\}$' # numers between 5 and 9 digist
> nolog.txt
Let's say we need to find count of multiple words in a file testfile.
There are two ways to go about it
1) Use grep command with regex matching pattern
grep -c '\<\(DOG\|CAT\)\>' testfile
2) Use egrep command
egrep -c 'DOG|CAT' testfile
With egrep you need not to worry about expression and just separate words by a pipe separator.
grep ‘string1\|string2’ FILENAME
GNU grep version 3.1
Place the strings you want to grep for into a file
echo who > find.txt
echo Roger >> find.txt
echo [44][0-9]{9,} >> find.txt
Then search using -f
grep -f find.txt BIG_FILE_TO_SEARCH.txt
grep '(string1.*string2 | string2.*string1)' filename
will get line with string1 and string2 in any order
for multiline match:
echo -e "test1\ntest2\ntest3" |tr -d '\n' |grep "test1.*test3"
or
echo -e "test1\ntest5\ntest3" >tst.txt
cat tst.txt |tr -d '\n' |grep "test1.*test3\|test3.*test1"
we just need to remove the newline character and it works!
You should have grep like this:
$ grep 'string1' file | grep 'string2'
I often run into the same problem as yours, and I just wrote a piece of script:
function m() { # m means 'multi pattern grep'
function _usage() {
echo "usage: COMMAND [-inH] -p<pattern1> -p<pattern2> <filename>"
echo "-i : ignore case"
echo "-n : show line number"
echo "-H : show filename"
echo "-h : show header"
echo "-p : specify pattern"
}
declare -a patterns
# it is important to declare OPTIND as local
local ignorecase_flag filename linum header_flag colon result OPTIND
while getopts "iHhnp:" opt; do
case $opt in
i)
ignorecase_flag=true ;;
H)
filename="FILENAME," ;;
n)
linum="NR," ;;
p)
patterns+=( "$OPTARG" ) ;;
h)
header_flag=true ;;
\?)
_usage
return ;;
esac
done
if [[ -n $filename || -n $linum ]]; then
colon="\":\","
fi
shift $(( $OPTIND - 1 ))
if [[ $ignorecase_flag == true ]]; then
for s in "${patterns[#]}"; do
result+=" && s~/${s,,}/"
done
result=${result# && }
result="{s=tolower(\$0)} $result"
else
for s in "${patterns[#]}"; do
result="$result && /$s/"
done
result=${result# && }
fi
result+=" { print "$filename$linum$colon"\$0 }"
if [[ ! -t 0 ]]; then # pipe case
cat - | awk "${result}"
else
for f in "$#"; do
[[ $header_flag == true ]] && echo "########## $f ##########"
awk "${result}" $f
done
fi
}
Usage:
echo "a b c" | m -p A
echo "a b c" | m -i -p A # a b c
You can put it in .bashrc if you like.
grep -i -w 'string1\|string2' filename
This works for exact word match and matching case insensitive words ,for that -i is used
When the both strings are in sequence then put a pattern in between on grep command:
$ grep -E "string1(?.*)string2" file
Example if the following lines are contained in a file named Dockerfile:
FROM python:3.8 as build-python
FROM python:3.8-slim
To get the line that contains the strings: FROM python and as build-python then use:
$ grep -E "FROM python:(?.*) as build-python" Dockerfile
Then the output will show only the line that contain both strings:
FROM python:3.8 as build-python
If git is initialized and added to the branch then it is better to use git grep because it is super fast and it will search inside the whole directory.
git grep 'string1.*string2.*string3'
searching for two String and highlight only string1 and string2
grep -E 'string1.*string2|string2.*string1' filename | grep -E 'string1|string2'
or
grep 'string1.*string2\|string2.*string1' filename | grep -E 'string1\|string2'
ripgrep
Here is the example using rg:
rg -N '(?P<p1>.*string1.*)(?P<p2>.*string2.*)' file.txt
It's one of the quickest grepping tools, since it's built on top of Rust's regex engine which uses finite automata, SIMD and aggressive literal optimizations to make searching very fast.
Use it, especially when you're working with a large data.
See also related feature request at GH-875.