I need to list all filenames which is having alien.digits
digits can be anytime from 1 to many
but it should not match if its the mixture of any other thing like alien.htm, alien.1php, alien.1234.pj.123, alien.123.12, alien.12.12p.234htm
I wrote:
find home/jassi/ -name "alien.[0-9]*"
But it is not working and its matching everything.
Any solution for that?
I think what you want is
find home/jassi/ -regex ".*/alien\.[0-9]+"
With -name option you don't specify a regular expression but a glob pattern.
Be aware that find expects that the whole path is matched by the regular expression.
Try this: find home/jassi/ -name "alien\.[0-9]+$"
It will match all files that have alien. and end with at least one digit but nothing else than digits. The $ character means end of string.
The * modifier means 0 or more of the previous match, and . means any character, which means it's matching alien.
Try this instead:
alien\.[0-9]+$
The + modifier means 1 or more of the previous match, and the . has been escaped to a literal character, and the $ on the end means "end of string".
You can also add a ^ to the start of the regex if you want to make sure that only files that exactly match your regex. The ^ character means "start of string", so ^alien\.[0-9]+$ will match alien.1234, but it won't match not_an_alien.1234.
It worked for me:
find home/jassi/ type -f -regex ".*/alien.[0-9]+"
I had to provide type -f to check if it's a file , else it would show the directory also of the same name.
Thanks bmk. I just figured out and at the same time you responded exactly the same thing. Great!
Related
Trying to find a command that is flexible enough to allow for some variations of the string, but not other variations of it.
For instance, I am looking for audio files that have some variation of "rain" in the filename only (rains, raining, rained, rainbow, rainfall, a dark rain cloud, etc), whether at the beginning, end or middle of the filename.
However, this also includes words like "brain", "train", "grain", "drain", "Lorraine", et al, which are not wanted (basically any word that has nothing to do with the concept of rain).
Something like this fails:
find . -name '*rain*' ! -name '*brain*'| more
And I'm having no luck with even getting started on building a successful regex variant because I cannot wrap my mind around regex ... for instance, this doesn't do anything:
# this is incomplete, just a stub of where I was going
# -type f also still includes a directory name
find . -regextype findutils-default -iregex '\(*rain*\)' -type f
Any help would be greatly appreciated. If I could see a regex command that does everything I want it to do, with an explanation of each character in the command, it would help me learn more about regex with the find command in general.
edit 1:
Taking cues from all the feedback so far from jhnc and Seth Falco, I have tried this:
find . -type f | grep -Pi '(?<![a-zA-Z])rain'
I think this pretty much works (I don't think it is missing anything), my only issue with it is that it also matches on occurrences of "rain" further up the path, not only in the file name. So I get example output like this:
./Linux/path/to/radiohead - 2007 - in rainbows/09 Jigsaw Falling Into Place.mp3
Since "rain" is not in the filename itself, this is a result I'd rather not see. So I tried this:
find . -type f -printf '%f\n' | grep -Pi '(?<![a-zA-Z])rain'
That does ensure that only filenames are matched, but it also does not output the paths to the filenames, which I would still like to see, so I know where the file is.
So I guess what I really need is a PCRE (PCRE2 ?) which can take the seemingly successful look-behind method, but only apply it after the last path delimiter (/ since I am on Linux), and I am still stumped.
specification:
match "rain"
in filename
only at start of a word
case-insensitive
assumptions:
define "word" to be sequence of letters (no punctuation, digits, etc)
paths have form prefix/name where prefix can have one or more levels delimited by / and name does not contain /
constraints:
find -iregex matches against entire path (-name only matches filename)
find -iregex must match entirety of path (eg. "c" is only a partial match and does not match path "a/b/c")
method:
find can return matches against non-files (eg. directories). Given definition 6, we would be unable to tell if name is a directory or an ordinary file. To satisfy 2, we can exclude non-files using find's -type f predicate.
We can compare paths found by find against our specification by using find's case-insensitive regex matching predicate (-iregex). The "grep" flavour (-regextype grep) is sufficiently expressive.
Just using 1, a suitable regex is: rain
2+6+7 says we must forbid / after "rain": rain[^/]*$
[/] matches character in set (ie. /)
[^/]: ^ inverts match: ie. character that is not /
* matches preceding match zero or more times
$ constrains preceding match to occur at end of input
3+5 says there must be no immediately preceding word characters: [^a-z]rain[^/]*$
a-z is a shortcut for the range a to z
8 requires matching the prefix explicitly: ^.*[^a-z]rain[^/]*$
^ outside of [...] constrains subsequent match to occur at beginning of input
. matches anything
[^a-z] matches a non-alphabetic
Final command-line:
find . -type f -regextype grep -iregex '^.*[^a-z]rain[^/]*$'
Note: The leading ^ and trailing $ are not actually required, given 8, and could be elided.
exercise for the reader:
extend "word" to non-ASCII characters (eg. UTF-8)
You probably want to use either a character class, word boundary, or just have a negative look behind for alpha characters.
Look Behind
^.+(?<![a-zA-Z])rain[^\/]*$
Matches any instance of rain, but only if it's not following [a-zA-Z], and doesn't have any slashes afterwards. Unfortunately, find doesn't support look ahead or look behind… so we'll use a character class instead.
Character Class
^.+(?:^|[^a-zA-Z])rain[^\/]*$
Matches the start of the line, or a character that isn't [a-zA-Z], then proceeds to match by the characters for rain if it comes immediately after, so long as there are no slashes afterwards.
You can use it in find like this:
find ./ -iregex '.+(?:^|[^a-zA-Z])rain[^\/]*'
The ^ at the start and $ at the end of the pattern are implied when using find with -iregex, so you can omit them.
PowerShell's New-PsDrive Cmdlet allows for drives to be created with more-flexible names like HKLM.
I'd like to match these drive\path\file patterns in the NavigationCmdletProvider that I'm building:
csb:
csb:\
csb:\foo\bar
csb:\foo\bar\
csb:\foo\bar bar\test.txt
but not these
csb:\\
csb:\\\
([a-zA-Z]+:)?(\\[a-zA-Z0-9_.-: :]+)*\\? matches everything that I want, but still includes the two that I don't. I can't seem to get it to match 0 or 1 \ at the end of the string.
What am I missing?
All you should need to do is tie your regular expression to the beginning and end of the line using a ^ and a $ respectively:
^([a-zA-Z]+:)?(\\[a-zA-Z0-9_.-: :]+)*\\?$
This is necessary almost any time you are trying to count a specific number of character in a regex.
I'm trying to search for whole word ending with .properties
So far this works:
find -E . -iregex '.*[:alnum:]+\.properties'
But I want to find only paths like
/some/path/messages.properties
and not
/some/path/messages_en.properties
The previous regex matches "en.properties" So, Im trying to say something like:
.*\/[:alnum:]+\.properties
That is, anything followed by slash then a word and then .properties but the slash part seems not to be working
You can use this regex with anchor $ on RHS and / on LHS to ensure filename is always complete:
find -E . -iregex '.*/[[:alnum:]]+\.properties$'
My understanding is that find traverses the entire file path to locate a string. As a result I cannot understand why the below regex is not working.
find / -regex '^sysconfig$'
Should return /etc/sysconfig.
Even simple regex such as find / -regex 'bin' returns nothing.
Am I missing something very simple?
Just change your regex to,
find / -regex '.*sysconfig$'
OR
find / -regex '.*/sysconfig$'
Because -regex find expression matches the whole name, including the relative path from the current directory. So .* at first will match the preceding characters.
In no regex implementation I'm aware of will the regex ^sysconfig$ match something like:
blah blah sysconfig
The ^ and $ are start-string and end-string anchors, meaning that your test string will only match if it is exactly sysconfig, with no other text on either side. And, in fact, they're not even needed since -regex matches the entire string rather than substrings.
If you want all files ending with sysconfig, just use:
find / - regex '.*sysconfig'
Or use '.*/sysconfig' if you want all files called sysconfig in any directory.
I am trying to search for the substring "abc" in a specific file in linux/bash
So I do:
grep '*abc*' myFile
It returns nothing.
But if I do:
grep 'abc' myFile
It returns matches correctly.
Now, this is not a problem for me. But what if I want to grep for a more complex string, say
*abc * def *
How would I accomplish it using grep?
The asterisk is just a repetition operator, but you need to tell it what you repeat. /*abc*/ matches a string containing ab and zero or more c's (because the second * is on the c; the first is meaningless because there's nothing for it to repeat). If you want to match anything, you need to say .* -- the dot means any character (within certain guidelines). If you want to just match abc, you could just say grep 'abc' myFile. For your more complex match, you need to use .* -- grep 'abc.*def' myFile will match a string that contains abc followed by def with something optionally in between.
Update based on a comment:
* in a regular expression is not exactly the same as * in the console. In the console, * is part of a glob construct, and just acts as a wildcard (for instance ls *.log will list all files that end in .log). However, in regular expressions, * is a modifier, meaning that it only applies to the character or group preceding it. If you want * in regular expressions to act as a wildcard, you need to use .* as previously mentioned -- the dot is a wildcard character, and the star, when modifying the dot, means find one or more dot; ie. find one or more of any character.
The dot character means match any character, so .* means zero or more occurrences of any character. You probably mean to use .* rather than just *.
Use grep -P - which enables support for Perl style regular expressions.
grep -P "abc.*def" myfile
The "star sign" is only meaningful if there is something in front of it. If there isn't the tool (grep in this case) may just treat it as an error. For example:
'*xyz' is meaningless
'a*xyz' means zero or more occurrences of 'a' followed by xyz
This worked for me:
grep ".*${expr}" - with double-quotes, preceded by the dot.
Where ${expr} is whatever string you need in the end of the line.
So in your case:
grep ".*abc.*" myFile
Standard unix grep.
The expression you tried, like those that work on the shell command line in Linux for instance, is called a "glob". Glob expressions are not full regular expressions, which is what grep uses to specify strings to look for. Here is (old, small) post about the differences. The glob expressions (as in "ls *") are interpreted by the shell itself.
It's possible to translate from globs to REs, but you typically need to do so in your head.
You're not using regular expressions, so your grep variant of choice should be fgrep, which will behave as you expect it to.
Try grep -E for extended regular expression support
Also take a look at:
The grep man page
'*' works as a modifier for the previous item. So 'abc*def' searches for 'ab' followed by 0 or more 'c's follwed by 'def'.
What you probably want is 'abc.*def' which searches for 'abc' followed by any number of characters, follwed by 'def'.
This may be the answer you're looking for:
grep abc MyFile | grep def
Only thing is... it will output lines were "def" is before OR after "abc"
$ cat a.txt
123abcd456def798
123456def789
Abc456def798
123aaABc456DEF
* matches the preceding character zero or more times.
$ grep -i "abc*def" a.txt
$
It would match, for instance "abdef" or "abcdef" or "abcccccccccdef". But none of these are in the file, so no match.
. means "match any character" Together with *, .* means match any character any number of times.
$ grep -i "abc.*def" a.txt
123abcd456def798
Abc456def798
123aaABc456DEF
So we get matches.
There are alot of online references about regular expressions, which is what is being used here.
I summarize other answers, and make these examples to understand how the regex and glob work.
There are three files
echo 'abc' > file1
echo '*abc' > file2
echo '*abcc' > file3
Now I execute the same commands for these 3 files, let's see what happen.
(1)
grep '*abc*' file1
As you said, this one return nothing. * wants to repeat something in front of it. For the first *, there is nothing in front of it to repeat, so the system recognize this * just a character *. Because the string in the file is abc, there is no * in the string, so you cannot find it. The second * after c means it repeat c 0 or more times.
(2)
grep '*abc*' file2
This one return *abc, because there is a * in the front, it matches the pattern *abc*.
(3)
grep '*abc*' file3
This one return *abcc because there is a * in the front and 2 c at the tail. so it matches the pattern *abc*
(4)
grep '.*abc.*' file1
This one return abc because .* indicate 0 or more repetition of any character.