I want to know What is the difference between the two command:
ls l file; grep *pl file
ls l file; grep ".*pl" file
First off - ";" is a command separator on shell. So the above will execute two different commands sequentially.
So that makes there are three different commands:
$ ls l file
This command will try to list two files namely "l" and "file". It will display the file names if they exist or error out if they do not.
$ grep *pl file
This is trickier. It will try to first replace * with the contents of the current directory. Whichever way it expands, it will append pl to it and try to grep that entire shell expanded pattern in the file. The output entirely depends upon the contents of your current directory.
$ grep ".*pl" file
This will do a greedy match of the pattern ".*pl" in the file. That means it will match all lines in the file which has a pattern: followed by "pl"
Try this yourself and you would understand what's happening.
Related
Tried the following command, it lists all the lines including file names
which are not matching the given pattern.
grep -nrv "^type.* = .*"
"But what we need is list of file names in a folder with content
which does not have even a single occurrence of above pattern."
Your help will be really appreciated.
You need the -L option:
grep -rL '^type.* = .*' directory_name
From the GNU grep manual:
-L, - -files-without-match
Suppress normal output; instead print the name of each input file from which no output would normally have been printed. The scanning will stop on the first match.
I am trying to get the most recent .CSV or .csv file name among other comma separated value files where the extension name is case insensitive.
I am achieving this with the following command, provided by someone else without any explanation:
ls -t ~(i:*.CSV) | head -1
or
ls -t -- ~(i:*.CSV) | head -1
I have two questions:
What is the use of ~ and -- in this case? Does -- helps here?
How can I get a blank response when there is no .csv or .CSV file in
the folder? At the moment I get:
/bin/ls: cannot access ~(i:*.CSV): No such file or directory
I know I can test the exit code of the last command, but I was wondering maybe there is a --silent option or something.
Many thanks for your time.
PS: I made my research online quite thorough and I was unable to find an answer.
The ~ is just a literal character; the intent would appear to be to match filenames starting with ~ and ending with .csv, with i: being a flag to make the match case-insensitive. However, I don't know of any shell that supports that particular syntax. The closest thing I am aware of would be zsh's globbing flags:
setopt extended_glob # Allow globbing flags
ls ~(#i)*.csv
Here, (#i) indicates that anything after it should be matched without regard to case.
Update: as #baptistemm points out, ~(i:...) is syntax defined by ksh.
The -- is a conventional argument, supported by many commands, to mean that any arguments that follow are not options, but should be treated literally. For example, ls -l would mean ls should use the -l option to modify its output, while ls -- -l means ls should try to list a file named -l.
~(i:*.CSV) is to tell to shell (this is only supported apparently in ksh93) the enclosed text after : must be treated as insensitive, so in this example that could all these possibilites.
*.csv or
*.Csv or
*.cSv or
*.csV or
*.CSv or
*.CSV
Note this could have been written ls -t *.[CcSsVv] in bash.
To silent errors I suggest you to look for in this site for "standard error /dev/null" that will help.
I tried running commands like what you have in both bash and zsh and neither worked, so I can't help you out with that, but if you want to discard the error, you can add 2>/dev/null to the end of the ls command, so your command would look like the following:
ls -t ~(i:*.CSV) 2>/dev/null | head -1
This will redirect anything written to STDERR to /dev/null (i.e. throw it out), which, in your case, would be /bin/ls: cannot access ~(i:*.CSV): No such file or directory.
I need to merge files in a directory and include the directory, filename, and line number in each line of the output. I've found many helpful posts about including the filename and line number but not the directory name. Grep -n gets line numbers and I've seen some find commands that get some of the other parts but I can't seem to pull them all together. (I'm using Ubuntu for all of the data processing.)
Imagine two files in directory named "8". (Each directory in the data I have is a number. The data were provided that way.)
file1.txt
JohnPaulGeorgeRingo
file2.txt
MickKeefBillBrianCharlie
The output should look like this:
8:file1.txt:1:John8:file1.txt:2:Paul8:file1.txt:3:George8:file1.txt:4:Ringo8:file2.txt:1:Mick8:file2.txt:2:Keef8:file2.txt:3:Bill8:file2.txt:4:Brian8:file2.txt:5:Charlie
The separators don't have to be colons. Tabs would work just fine.
Thanks much!
If it's just one directory level deep you could try something like so. We go into each directory, print each line with its number and then append the directory name to the front with sed:
$ for x in `ls`; do
(cd $x ; grep -n . *) | sed -e 's/^/'$x:'/g'
done
1:c.txt:2:B
1:c.txt:3:C
2:a.txt:1:A
2:a.txt:2:B
In my script shell, i have 2 files. The first one is a file containing only names of files with part of the path :
list1:
aaa/bbb/file1.ext
ccc/ddd/file2.ext
eee/fff/file3.ext
The second one is a list of every files of the extension ".ext" with the absolute path before them:
list2:
/home/.../aaa/bbb/file1.ext
...
...
...
/home/...ccc/ddd/file2.ext
...
And I am trying to extract the lines of the second file list2, containing the lines of the first one with grep.
For now I tried :
while read line
do
grep "$line" "list1"
done < list2
But this command doesn't ouptut anything, however the command
grep "aaa/bbb/file1.ext" "list1"
have the output I am waiting for
/home/.../aaa/bbb/file1.ext
Anyone sees what I am missing on this script? Thanks
This is one of the cases where -f option from grep comes very handy:
grep -f f1 f2
For your given input returns:
/home/.../aaa/bbb/file1.ext
/home/...ccc/ddd/file2.ext
From man grep:
-f FILE, --file=FILE
Obtain patterns from FILE, one per line. The empty file contains zero
patterns, and therefore matches nothing. (-f is specified by
POSIX.)
I am performing a recursive fgrep/grep -f search on a zipped up folder using the following command in one of my programs:
The command I am using:
grep -r -i -z -I -f /path/to/pattern/file /home/folder/TestZipFolder.zip
Inside the pattern file is the string "Dog" that I am trying to search for.
In the zipped up folder there are a number of text files containing the string "Dog".
The grep -f command successfully finds the text files containing the string "Dog" in 3 files inside the zipped up folder, but it prints the output all on one line and some strange characters appear at the end i.e PK (as shown below). And when I try and print the output to a file in my program other characters appear on the end such as ^B^T^#
Output from the grep -f command:
TestZipFolder/test.txtThis is a file containing the string DogPKtest1.txtDog, is found again in this file.PKTestZipFolder/another.txtDog is written in this file.PK
How would I get each of the files where the string "Dog" has been found to print on a new line so they are not all grouped together on one line like they are now?
Also where are the "PK" and other strange characters appearing from in the output and how do i prevent them from appearing?
Desired output
TestZipFolder/test.txt:This is a file containing the string Dog
TestZipFolder/test1.txt:Dog, is found again in this file
TestZipFolder/another.txt:Dog is written in this file
Something along these lines, whereby the user is able to see where the string can be found in the file (you actually get the output in this format if you run the grep command on a file that is not a zip file).
If you need a multiline output, better use zipgrep :
zipgrep -s "pattern" TestZipFolder.zip
the -s is to suppress error messages(optional). This command will print every matched lines along with the file name. If you want to remove the duplicate names, when more than one match is in a file, some other processing must be done using loops/grep or awk or sed.
Actually, zipgrep is a combination egrep and unzip. And its usage is as follows :
zipgrep [egrep_options] pattern file[.zip] [file(s) ...] [-x xfile(s) ...]
so you can pass any egrep options to it.