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I want to search for a string (which I don't know unless I look inside the files) on Linux command-line.
Example:
A file 1 with text inside
A file 2 with text inside
In both files the word "Apple" is existent.
I want to echo this word (which exists in both files) in a file or store it in a variable.
How is this possible?
You can get a list of all the unique words in a file using:
grep -o -E '\w+' filename | sort -u
where -E '\w+' is matching words and -o outputs the matching parts. We can then use the join command which identifies matching lines in two files, along with process substitution to pass in the results of our word finder:
join <(grep -o -E '\w+' filename1 | sort -u) <(grep -o -E '\w+' filename2 | sort -u)
If there are no duplicates whiten a single file you could use cat file1 file2 |sort | uniq -d
$ cat input_one.txt
FIREFOX a
FIREFOX b
Firefox a
firefox b
$ cat input_two.txt
CHROME a
FIREFOX a
EXPLORER a
$ while read line; do grep "$line" input_two.txt ; done < input_one.txt
FIREFOX a
Explanation:
while will loop every line with input_two.txt file as input and will store the temporary line in the line variable.
In every line will search for it in the input_one.txt file and -o option will make to print only the matched part.
EDIT: See comments
You can write the script to handle this.
You need loop a word on file 1, in the loop use grep command (grep -nwr "" -e "$word") to find a word in file 2.
If match, echo a word.
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I want to search for a String by navigating to a particular line, How to do this in shell scripting?
For example,
I have
this is the first line
this is the Second line
This is the Third line
Now here i would want to look for string "Third" by going to 3rd line.
Any help is appreciated, Thank you.
Try stringing together cat, sed, and grep.
sed '3!d' filename | grep Third
The unnamed or anonymous pipe (|) and redirection (<, >) are powerful features of many shells. They allow one to combine a set of commands to perform a more complex function.
In the case of this question there were two clear steps,
1) Operate on a specific line of a file (e.g. filter a file)
2) Search the output of the filter for a specific string
Recognizing that there were two steps is a strong indicator that two commands will need to be combined. Therefore, the problem can be solved by finding a solution to each step and then combining them in to one command with pipes and redirection.
If you know about the Stream Editor (sed), it may come to your mind when thinking about how to accomplish the first step of filtering the file. If not searching for, "linux get a specific line of a file" this OS question comes up high in the search results.
$ cat tmp.txt
this is the first line
this is the Second line
This is the Third. line
$ sed '3!d' tmp.txt
This is the Third. line
Knowing that grep can be search for lines with the string of interest the next challenge is to figure out how to get the output of sed as the input to grep. The pipe (|) solves this problem.
sed '3!d' filename | grep Third
Example output:
$ sed '3!d' tmp.txt | grep Third
This is the Third. line
$
Another powerful concept in shell scripting is the exit status. The grep command will set the exit status to 0 when a match is found and 1 when a match is not found. The shell stores the exit status in a special variable named $? (for bash). Therefore, one could use the exit status to conditionally determine the next step in the shell script. The example below does not implement conditions (like if, else). The example below shows the exit status value using the echo command.
$ sed '3!d' tmp.txt | grep Third
This is the Third. line
$ echo $?
0
$ sed '3!d' tmp.txt | grep third
$ echo $?
1
$
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Suppose I have a file with warnings. Each warning in a new line with an id that has 3 capital letters followed by 3 digits only, should be replaced by its id.
Example:
SIM_WARNING[ANA397]: Node q<159> for vector output signal does not exist
The output should be ANA397 and the rest of line is deleted.
How to do so using sed?
I don't think you need sed for that. A simple grep with --only-matching could do, as in:
grep -E 'SIM_WARNING\[(.)\]' --only-matching
should work for you.
Where:
-E does "enhanced regular expressions. I think we need those for capturing with ( )
then follows the pattern, which consists of the fixed SIM_WARNING, followed by a match inside the square brackets
--only-matching simply makes grep print only matching content
In other words: by using ( match ) you tell grep that you only care about the thing in that match pattern.
for id in $(grep -o "^SIM_WARNING\[[A-Z][A-Z][A-Z][0-9][0-9][0-9]\]" test1.bla | grep -o "[A-Z][A-Z][A-Z][0-9][0-9][0-9]" test1.bla ); do echo $id; done
This finds ANA397 from the below.
SIM_WARNING[ANA397]: Node q<159> for vector output signal does not exist
First of all, you have to choose how to use the IDs, for example if you need to cycle the file first or the IDs later...
E.G. (Cycle file first)
exec 3<file
while read -r line <&3; do
id="$(printf "%s" "${line}" | sed -e "s/.*\[\([[:alnum:]]\+\)\].*/\1/")"
### Do something with id
done
exec 3>&-
Otherwise you can decide to cycle the output of sed...
E.G.
for id in $(sed -e "s/.*\[\([[:alnum:]]\+\)\].*/\1/" file); do
### Do something with id
done
Both of the examples should work with posix shell (If I am not missing something...), but shell like posh may not support classes as [[:alnum:]], you can substitute them with the equivalent [a-zA-Z0-9], as every guide will teach you.
Note that the check is not on 3 letters and 3 digits, but for any letter and digit between brackets ([ and ]).
EDIT:
If your lines start with SIM_WARNING you can discriminates those lines with -e "/^SIM_WARNING/! d"
For a strict check on 3 letters and 3 digits you can use -e "s/.*\[\([a-zA-Z][a-zA-Z][a-zA-Z][0-9][0-9][0-9]\)\].*/\1/"
So taking the example above you can do somethin like:
for id in $(sed -e "/^SIM_WARNING/! d" -e "s/.*\[\([a-zA-Z][a-zA-Z][a-zA-Z][0-9][0-9][0-9]\)\].*/\1/" file)
### Do something with id
done
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I am writing a bash script to check if an array element is in a file.
For example:
I have an array of errors errors=("1234" "5678" "9999")
I have a file that contains patterns of strings
123400 452612 9999A0 1010EB
I am looking to loop over the file that contains the errors and check to see if any of the array elements matches any string pattern in the file. If it does then give me back the exact array pattern it matched in the file for further processing.
Any ideas on how I can do this?
Here's a way where you only need to invoke grep once:
$ grep -oFf <(printf "%s\n" "${errors[#]}") file
1234
9999
The -f option is to specify a file that contains the pattern. I use a process substitution to "contain" the patterns, one per line.
The -F option specifies plain-text matching: I assume your "errors" array won't contain regular expressions.
Sounds like you just want a loop:
for error in "${errors[#]}"; do
if grep -qE "(^| )$error( |\$)" file; then
# $error was found in the file
fi
done
This matches the error preceded by the start of the line or a space, and followed by a space or the end of the line.
I made an effort to not match appearances of the errors within substrings but if you don't care, then you could change the grep command to this:
grep -qF "$error" file
This will return success if the error string occurs anywhere on the line.
The script goes like this,
#/bin/bash
errors=("1234" "5678" "9999")
for error in "${errors[#]}"
do
grep -o "$error" file
done
For a sample file,
$ cat file
123400 452612 9999A0 1010EB
The script produces an output
$ ./script.sh
1234
9999
meaning the above two keys from the array have matched in the file. The -o flag in grep is to identify only the matching parts from the array. An excerpt from the man grep page.
-o, --only-matching
Print only the matched (non-empty) parts of a matching line, with each such part on a separate output line.
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Can't use awk or sed or any other string processing utilities
Any help on this problem is appreciated I have a text file with the following format
BobJanitor20000
TedBuilder30000
NedFighter25000
KitTeacher40000
yes, assume that the names are always three characters long, profession 7 characters and salary 5 characters edit: varaibles come from user input and not as a parameters
I ask the user for a name input and another input whether to display occupation or Salary
If the user enters "Ted" and chooses salary, the output should be
Ted 30000
The program must also take into account partial name matches, "ed" and salary should output
Ted 30000
Ned 25000
I know cut and grep can get me the relavent lines but how do i create the output i want?
cut -c1-3 textFile| grep "$user_input"
gets me the lines i want to use but how do i isolate the Name and profession columns and then the name and salary columns
You must split the input lines in fields first. Something like grep "$user_input" textFile will fail when the input matches a part of the job.
For this reason a simple approach with grep will fail:
With grep you have the option -o to show the matching part only. Combine this with a dot for a single character, and ^ for the beginning of a line or a $ for the end of the line.
# Show salary
# echo "TedBuilder30000" | grep "Ted" | grep -o ".....$"
# Show job
# echo "TedBuilder30000" | grep "Ted" | grep -o "............$" | grep -o "^......."
This will become messy when you want to show the matched name (Ted/Ned) as well.
So how do we split everything up?
I already stored the userinput for name and display in variables. The display is converted in lowercase automaticly with the typeset -l.
userinput=ed
typeset -l display
display=Salary
while read line; do
# offset 0, length 3
name=${line:0:3}
job=${line:3:7}
sal=${line:10:5}
# echo "Debug: Name=$name Job=$job Sal=$sal"
# double brackets for matching the userinput with wildcards
if [[ "$name" = *${userinput}* ]]; then
# Use case for a switch between different possible values
case "${display}" in
"occupation|job") echo "${name} ${job}";;
"salary") echo "${name} ${sal}";;
*) echo "Unsupported display ${display}";;
esac
fi
done < testFile # While reads from testFile, I avoid using cat (Google for uuoc)
You may want:
grep "$user_input" textFile | tee >(cut -c '11-15') | echo `cut -c 1-2`
This is called process substitution.
See https://unix.stackexchange.com/questions/28503/how-can-i-send-stdout-to-multiple-commands
You can use cut with character ranges, for example
echo NedFighter25000 | cut -c 1-3
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I have this script I'm studying and I would like to know what is cat doing in this section.
if cat downloaded.txt | grep "$count" >/dev/null
then
echo "File already downloaded!"
else
echo $count >> downloaded.txt
cat $count | egrep -o "http://server.*(png|jpg|gif)" | nice -n -20 wget --no-dns-cache -4 --tries=2 --keep-session-cookies --load-cookies=cookies.txt --referer=http://server.com/wallpaper/$number -i -
rm $count
fi
Like most cats, this is a useless cat.
Instead of:
if cat downloaded.txt | grep "$count" >/dev/null
It could have been written:
if grep "$count" download.txt > /dev/null
In fact, because you've eliminated the pipe, you've eliminated issues with which exit value the if statement is dealing with.
Most Unix cats you'll see are of the useless variety. However, people like cats almost as much as they like using a grep/awk pipe, or using multiple grep or sed commands instead of combining everything into a single command.
The cat command stands for concatenate which is to allow you to concatenate files. It was created to be used with the split command which splits a file into multiple parts. This was useful if you had a really big file, but had to put it on floppy drives that couldn't hold the entire file:
split -b140K -a4 my_really_big_file.txt my_smaller_files.txt.
Now, I'll have my_smaller_files.txt.aaaa and my_smaller_files.txt.aaab and so forth. I can put them on the floppies, and then on the other computer. (Heck, I might go all high tech and use UUCP on you!).
Once I get my files on the other computer, I can do this:
cat my_smaller_files.txt.* > my_really_big_file.txt
And, that's one cat that isn't useless.
cat prints out the contents of the file with the given name (to the standard output or to wherever it's redirected). The result can be piped to some other command (in this case, (e)grep to find something in the file contents). Concretely, here it tries to download the images referenced in that file, then adds the name of the file to downloaded.txt in order to not process it again (this is what the check in if was about).
http://www.linfo.org/cat.html
"cat" is a unix command that reads the contents of one or more files sequentially and by default prints out the information the user console ("stdout" or standard output).
In this case cat is being used to read the contents of the file "downloaded.txt", the pipe "|" is redirecting/feeding its output to the grep program, which is searching for whatever is in the variable "$count" to be matched with.