I am trying to figure out how to search a file for example test.txt for "#include" and print the first instance of it that is found. However if it is not found I want to print out the whole file. I can do the first part with grep "#include" test.txt | head -n 1 but can't seem to figure out how to include the second requirement.
grep -m 1 '#include' "$file" || cat "$file"
You can control grep's output in many ways with grep options.
grep exits non-success status if the match is not found.
Related
I am running the following command:
for file in 2017120[1-9]/54100_*.zip; do unzip -c "$file" | grep "3613825" | grep '3418665' ; done
This does a grep job of pulling the data that matches my grep parameters, but I can't figure out how to capture which file the results came from.
I have tried adding grep -H but the result comes back with (standard input).
How can I capture the file name?
When I need to do something like this I just add an echo of the file name to the for loop like this:
for file in 2017120[1-9]/54100_*.zip; do echo $file; unzip -c "$file" | grep "3613825" | grep '3418665' ; done
This prints out the list of files, and the grep line that matches will print immediately after the file that the match is in. like this:
file_1
file_2
file_3
matching line
file_4
file_5
another matching line
file_6
...
Thus I know the matching lines occurred in file_3 and file_5.
I have a large log file where I am currently running two commands. I search the log group and then make a filtered file where I return the following 3 lines after a match:
cat testFile.log |grep 'Text I am looking for' -A 3 > filter.txt
Then once I have my filtered file, I scan through that file to create myself a final file of the values I want:
cat filter.txt | grep -E 'Data\w{7}' -o > final.txt
My aim is to do this in one line if possible so I can wrap a bunch of these checks together in a script so I can jump in and search x,y,z and then I get a set of finalised files at the end for each one.
You just need to make use of pipes. That is, the UNIX core way of thinking in which small pieces are grouped together to create a beautiful tool.
In this case you have to orders:
grep 'Text I am looking for' -A 3 testFile.log > filter.txt # 1
grep -E 'Data\w{7}' -o filter.txt > final.txt # 2
(Note I removed the cat file | grep '...' since it is the same as saying grep '...' file)
Since the output of #1 is to feed #2, just use pipes:
grep -A 3 'Text I am looking for' testFile.log | grep -Eo 'Data\w{7}' > final.txt
This way you prevent the use of an unnecessary intermediate file.
I have practiced in using command line in CentOS6.
I tried to create file, which content would be the output of command man grep. Also I used command man with col -b option to save file as Text-Only. All of this must be in one command.
I tried to do like this:
grep man grep | col -b > output.txt
But it didn't work.
What is the proper way to save output of command man grep as Text-Only file with using option col -b?
Don't you really need this:
man grep | col -b > output.txt
Why do you need to call grep in the first place?
Other, hacky way using grep:
man grep | grep -v somephrasethatwontoccur | col -b > output.txt
But, truly, it makes no sense. grep -v looks for lines without the specified phrase.
In a very large file I need to find the position (line number) of a string, then extract the 2 lines above and below that string.
To do this right now - I launch vi, find the string, note it's line number, exit vi, then use sed to extract the lines surrounding that string.
Is there a way to streamline this process... ideally without having to run vi at all.
Maybe using grep like this:
grep -n -2 your_searched_for_string your_large_text_file
Will give you almost what you expect
-n : tells grep to print the line number
-2 : print 2 additional lines (and the wanted string, of course)
You can do
grep -C 2 yourSearch yourFile
To send it in a file, do
grep -C 2 yourSearch yourFile > result.txt
Use grep -n string file to find the line number without opening the file.
you can use cat -n to display the line numbers and then use awk to get the line number after a grep in order to extract line number:
cat -n FILE | grep WORD | awk '{print $1;}'
although grep already does what you mention if you give -C 2 (above/below 2 lines):
grep -C 2 WORD FILE
You can do it with grep -A and -B options, like this:
grep -B 2 -A 2 "searchstring" | sed 3d
grep will find the line and show two lines of context before and after, later remove the third one with sed.
If you want to automate this, simple you can do a Shell Script. You may try the following:
#!/bin/bash
VAL="your_search_keyword"
NUM1=`grep -n "$VAL" file.txt | cut -f1 -d ':'`
echo $NUM1 #show the line number of the matched keyword
MYNUMUP=$["NUM1"-1] #get above keyword
MYNUMDOWN=$["NUM1"+1] #get below keyword
sed -n "$MYNUMUP"p file.txt #display above keyword
sed -n "$MYNUMDOWN"p file.txt #display below keyword
The plus point of the script is you can change the keyword in VAL variable as you like and execute to get the needed output.
How do I pipe the output of grep as the search pattern for another grep?
As an example:
grep <Search_term> <file1> | xargs grep <file2>
I want the output of the first grep as the search term for the second grep. The above command is treating the output of the first grep as the file name for the second grep. I tried using the -e option for the second grep, but it does not work either.
You need to use xargs's -i switch:
grep ... | xargs -ifoo grep foo file_in_which_to_search
This takes the option after -i (foo in this case) and replaces every occurrence of it in the command with the output of the first grep.
This is the same as:
grep `grep ...` file_in_which_to_search
Try
grep ... | fgrep -f - file1 file2 ...
If using Bash then you can use backticks:
> grep -e "`grep ... ...`" files
the -e flag and the double quotes are there to ensure that any output from the initial grep that starts with a hyphen isn't then interpreted as an option to the second grep.
Note that the double quoting trick (which also ensures that the output from grep is treated as a single parameter) only works with Bash. It doesn't appear to work with (t)csh.
Note also that backticks are the standard way to get the output from one program into the parameter list of another. Not all programs have a convenient way to read parameters from stdin the way that (f)grep does.
I wanted to search for text in files (using grep) that had a certain pattern in their file names (found using find) in the current directory. I used the following command:
grep -i "pattern1" $(find . -name "pattern2")
Here pattern2 is the pattern in the file names and pattern1 is the pattern searched for
within files matching pattern2.
edit: Not strictly piping but still related and quite useful...
This is what I use to search for a file from a listing:
ls -la | grep 'file-in-which-to-search'
Okay breaking the rules as this isn't an answer, just a note that I can't get any of these solutions to work.
% fgrep -f test file
works fine.
% cat test | fgrep -f - file
fgrep: -: No such file or directory
fails.
% cat test | xargs -ifoo grep foo file
xargs: illegal option -- i
usage: xargs [-0opt] [-E eofstr] [-I replstr [-R replacements]] [-J replstr]
[-L number] [-n number [-x]] [-P maxprocs] [-s size]
[utility [argument ...]]
fails. Note that a capital I is necessary. If i use that all is good.
% grep "`cat test`" file
kinda works in that it returns a line for the terms that match but it also returns a line grep: line 3 in test: No such file or directory for each file that doesn't find a match.
Am I missing something or is this just differences in my Darwin distribution or bash shell?
I tried this way , and it works great.
[opuser#vjmachine abc]$ cat a
not problem
all
problem
first
not to get
read problem
read not problem
[opuser#vjmachine abc]$ cat b
not problem xxy
problem abcd
read problem werwer
read not problem 98989
123 not problem 345
345 problem tyu
[opuser#vjmachine abc]$ grep -e "`grep problem a`" b --col
not problem xxy
problem abcd
read problem werwer
read not problem 98989
123 not problem 345
345 problem tyu
[opuser#vjmachine abc]$
You should grep in such a way, to extract filenames only, see the parameter -l (the lowercase L):
grep -l someSearch * | xargs grep otherSearch
Because on the simple grep, the output is much more info than file names only. For instance when you do
grep someSearch *
You will pipe to xargs info like this
filename1: blablabla someSearch blablabla something else
filename2: bla someSearch bla otherSearch
...
Piping any of above line makes nonsense to pass to xargs.
But when you do grep -l someSearch *, your output will look like this:
filename1
filename2
Such an output can be passed now to xargs
I have found the following command to work using $() with my first command inside the parenthesis to have the shell execute it first.
grep $(dig +short) file
I use this to look through files for an IP address when I am given a host name.