Was hoping someone can help out with this. I am trying to figure out how to display the first line that contains a certain string i.e. "computer" (first occurrence of "computer" in a txt file). I would prefer to do this using grep.
I know grep "computer" somefile.txt
would display all of the lines including "computer".
I am eager to learn and if anyone has alternative ways I would like to hear!
Thx everyone
Use the match count option of grep
grep -m 1 "computer" somefile.txt
Note that grep is non standard across un*x's so while http://www.gnu.org/software/grep/ supports this, if your distro or unix does not this will not work.
Pipes are your friend:
grep "computer" somefile.txt | head -n1
Is this homework?
grep -v "computer" somefile.txt | head -n 1
Comes to mind the quickest.
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.
I am trying to find the number of lines that contain the word. I realize this is possible with the wc command and the -l flag, but I'm not 100% sure how to do it. Any ideas?
Instead of wc, you can use grep like this:
grep -c "word" file
I have a file in the location /home/someuser/sometext.txt . I want to count the number of lines in which a particular string occurs. What's the way to do that from Linux command line?
grep with -c switch is what you need:
grep -c "pattern" /home/someuser/sometext.txt
Alternate solution using awk:
awk '/regex/{c++}END{print c+0}' /home/someuser/sometext.txt
You're looking for the grep command. Here's a basic tutorial. It's extremely useful for string searching in files. It also has support for regular expressions.
It looks like you'll do something like this:
grep -c "mystring" /home/someuser/sometext.txt
The -c argument is short for --count and tells grep to print out the number of lines that contain the string.
The line I seek is stored in the file data.txt and is the only line of text that occurs only once.
How do I go about finding that particular line using linux?
This is a little bit old, but I think you are looking for this...
cat data.txt | sort | uniq -u
This will show the unique values that only occur once in the file. I assume you are familiar with "over the wire" if you are asking?? If so, this is what you are looking for.
To provide some context (I need more rep to comment) this is a question that features in an online "wargame" called Bandit that involves using the command line to discover passwords on an online Linux server to advance up the levels.
For those who would like to see data.txt in full I've Pastebin'd it here however it looks like this:
NN4e37KW2tkIb3dC9ZHyOPdq1FqZwq9h
jpEYciZvDIs6MLPhYoOGWQHNIoQZzE5q
3rpovhi1CyT7RUTunW30goGek5Q5Fu66
JOaWd4uAPii4Jc19AP2McmBNRzBYDAkO
JOaWd4uAPii4Jc19AP2McmBNRzBYDAkO
9WV67QT4uZZK7JHwmOH0jnhurJMwoGZU
a2GjmWtTe3tTM0ARl7TQwraPGXgfkH4f
7yJ8imXc7NNiovDuAl1ZC6xb0O0mMBx1
UsvVyFSfZZWbi6wgC7dAFyFuR6jQQUhR
FcOJhZkHlnwqcD8QbvjRyn886rCrnWZ7
E3ugYDa6Wh2y8C8xQev7vOS8O3OgG1Hw
E3ugYDa6Wh2y8C8xQev7vOS8O3OgG1Hw
ME7nnzbId4W3dajsl6Xtviyl5uhmMenv
J5lN3Qe4s7ktiwvcCj9ZHWrAJcUWEhUq
aouHvjzagN8QT2BCMB6e9rlN4ffqZ0Qq
ZRF5dlSuwuVV9TLhHKvPvRDrQ2L5ODfD
9ZjR3NTHue4YR6n4DgG5e0qMQcJjTaiM
QT8Bw9ofH4x3MeRvYAVbYvV1e1zq3Xim
i6A6TL6nqvjCAPvOdXZWjlYgyvqxmB7k
tx7tQ6kgeJnC446CHbiJY7fyRwrwuhrs
One way to do it is to use:
sort data.txt | uniq -u
The sort command is like cat in that it displays the contents of the file however it sorts the file lexicographically by lines (it reorders them alphabetically so that matching ones are together).
The | is a pipe that redirects the output from one command into another.
The uniq command reports or omits repeated lines and by passing it the -u argument we tell it to report only unique lines.
Used together like this, the command will sort data.txt lexicographically by each line, find the unique line and print it back in the terminal for you.
sort -u data.txt | while read line; do if [ $(grep -c $line data.txt) == 1 ] ;then echo $line; fi; done
was mine solution, until I saw here easy one:
sort data.txt | uniq -u
Add more information to you post.
How data.txt look like?
Like this:
11111111
11111111
pass1111
11111111
Or like this
afawfdgd
password
somethin
gelse...
And, do you know the password is in file or you search for not repeat string.
If you know password, use something like this
cat data.txt | grep 'password'
If you don`t know the password and this password is only unique line in file you must create a script.
For example in Python
file = open("data.txt","r")
f = file.read()
for line in f:
if 'pass' in line:
print pass
Of course replace pass with something else.
For example some slice from line.
And one with only one tool in use, awk:
awk '{a[$1]++}END{for(i in a){if(a[i] == 1){print i} }}' data.txt
sort data.txt | uniq -c | grep 1\ ?*
and it will print the only text that occurs only one time
do not forget to put space after the backslash
sort data.txt | uniq -c | grep 1
you will find only one that accures one time
This question already has answers here:
Colorized grep -- viewing the entire file with highlighted matches
(24 answers)
Closed 7 years ago.
When using grep, it will highlight any text in a line with a match to your regular expression.
What if I want this behaviour, but have grep print out all lines as well? I came up empty after a quick look through the grep man page.
Use ack. Checkout its --passthru option here: ack. It has the added benefit of allowing full perl regular expressions.
$ ack --passthru 'pattern1' file_name
$ command_here | ack --passthru 'pattern1'
You can also do it using grep like this:
$ grep --color -E '^|pattern1|pattern2' file_name
$ command_here | grep --color -E '^|pattern1|pattern2'
This will match all lines and highlight the patterns. The ^ matches every start of line, but won't get printed/highlighted since it's not a character.
(Note that most of the setups will use --color by default. You may not need that flag).
You can make sure that all lines match but there is nothing to highlight on irrelevant matches
egrep --color 'apple|' test.txt
Notes:
egrep may be spelled also grep -E
--color is usually default in most distributions
some variants of grep will "optimize" the empty match, so you might want to use "apple|$" instead (see: https://stackoverflow.com/a/13979036/939457)
EDIT:
This works with OS X Mountain Lion's grep:
grep --color -E 'pattern1|pattern2|$'
This is better than '^|pattern1|pattern2' because the ^ part of the alternation matches at the beginning of the line whereas the $ matches at the end of the line. Some regular expression engines won't highlight pattern1 or pattern2 because ^ already matched and the engine is eager.
Something similar happens for 'pattern1|pattern2|' because the regex engine notices the empty alternation at the end of the pattern string matches the beginning of the subject string.
[1]: http://www.regular-expressions.info/engine.html
FIRST EDIT:
I ended up using perl:
perl -pe 's:pattern:\033[31;1m$&\033[30;0m:g'
This assumes you have an ANSI-compatible terminal.
ORIGINAL ANSWER:
If you're stuck with a strange grep, this might work:
grep -E --color=always -A500 -B500 'pattern1|pattern2' | grep -v '^--'
Adjust the numbers to get all the lines you want.
The second grep just removes extraneous -- lines inserted by the BSD-style grep on Mac OS X Mountain Lion, even when the context of consecutive matches overlap.
I thought GNU grep omitted the -- lines when context overlaps, but it's been awhile so maybe I remember wrong.
You can use my highlight script from https://github.com/kepkin/dev-shell-essentials
It's better than grep cause you can highlight each match with it's own color.
$ command_here | highlight green "input" | highlight red "output"
Since you want matches highlighted, this is probably for human consumption (as opposed to piping to another program for instance), so a nice solution would be to use:
less -p <your-pattern> <your-file>
And if you don't care about case sensitivity:
less -i -p <your-pattern> <your-file>
This also has the advantage of having pages, which is nice when having to go through a long output
You can do it using only grep by:
reading the file line by line
matching a pattern in each line and highlighting pattern by grep
if there is no match, echo the line as is
which gives you the following:
while read line ; do (echo $line | grep PATTERN) || echo $line ; done < inputfile
If you want to print "all" lines, there is a simple working solution:
grep "test" -A 9999999 -B 9999999
A => After
B => Before
If you are doing this because you want more context in your search, you can do this:
cat BIG_FILE.txt | less
Doing a search in less should highlight your search terms.
Or pipe the output to your favorite editor. One example:
cat BIG_FILE.txt | vim -
Then search/highlight/replace.
If you are looking for a pattern in a directory recursively, you can either first save it to file.
ls -1R ./ | list-of-files.txt
And then grep that, or pipe it to the grep search
ls -1R | grep --color -rE '[A-Z]|'
This will look of listing all files, but colour the ones with uppercase letters. If you remove the last | you will only see the matches.
I use this to find images named badly with upper case for example, but normal grep does not show the path for each file just once per directory so this way I can see context.
Maybe this is an XY problem, and what you are really trying to do is to highlight occurrences of words as they appear in your shell. If so, you may be able to use your terminal emulator for this. For instance, in Konsole, start Find (ctrl+shift+F) and type your word. The word will then be highlighted whenever it occurs in new or existing output until you cancel the function.