I can add "06:00" to the command: Apr 5 06:00:01 smatteso-vm1 audispd: node=smatteso-vm1 type=USER_ACCT msg=audit(1491386401.774:143444): user pid=33946 uid=0 auid=4294967295 ses=4294967295 msg='op=PAM:accounting acct="phxinst1" exe="/usr/sbin/crond" hostname=? This flag tells grep to print the matching filenames. for nested folders; "/" for the entire file system; "~" for the active user's home directory. Similarly, if you want to find the number of directories only inside a directory, use the below command. You can search the entire file system by changing that "/etc" to "/": (note this can be quite a time-consuming operation!). Special characters are used to define the matching rules and positions. Search for the given string in a single file. It also supports showing the context of a match by showing lines before and after the result and has support for regular expressions in pattern matching. The basic syntax of grep command is shown below: grep -irhnwl "search string" "directory-path" Where:-i: Used to ignore case sensitive string.-r: Used to search directory recursively.-h: Used to suppress the inclusion of the file names in the output. The result of this is the occurences of the pattern (by the line it is found) in the file(s). Let's say that we wanted to search through a directory, and wanted to find … Start and End of Lines I can use the find command and pipe the results to grep as follows: find. By using the grep command, you can customize how the tool searches for a pattern or multiple patterns in this case. Tweet a thanks, Learn to code for free. You can also use grep to search for multiple words: grep -r … As you can see, grep searched multiple directories and indicates where it found the string. With a clever arrangement of syntax, you can use find’s faster file-system search to locate the specific file types you want to search within, then pipe them to grep in order to search inside the files. terminal=cron res=success', Apr 5 06:00:01 smatteso-vm1 audispd: node=smatteso-vm1 type=USER_ACCT msg=audit(1491386401.774:143445): user pid=33945 uid=0 auid=4294967295 ses=4294967295 msg='op=PAM:accounting acct="phxinst1" exe="/usr/sbin/crond" hostname=? You may not want to actually see the output of the grep command but have it tell you how many matches your search found. Look for a string, word, or sentence in a file with Linux grep command, recursively. TechRepublic Premium: The best IT policies, templates, and tools, for today and tomorrow. The grep command allows searching for a text or string in a file or from output console of a command, for a term or pattern matching regular expressions. This command permits you to check for multiple words in a file - note the use of the single quotes, the backslash and the pipe command between them: Apr 2 03:45:07 smatteso-vm1 sshd[16278]: Connection closed by 10.1.7.101, Apr 2 03:46:42 smatteso-vm1 su: pam_unix(su-l:session): session opened for user phxinst1 by (uid=0), Apr 2 03:46:45 smatteso-vm1 su: pam_unix(su-l:session): session closed for user phxinst1, Apr 2 03:46:45 smatteso-vm1 su: pam_unix(su-l:session): session opened for user phxinst1 by (uid=0). There are multiple versions of grep; plain regular grep, egrep (extended grep) and fgrep (fixed prep). You can also look for a specific process identifier. It searches for a particular expression pattern in a specified file. Say I want to see everything logged on April 5th: Apr 5 00:00:01 smatteso-vm1 audispd: node=smatteso-vm1 type=USER_ACCT msg=audit(1491364801.741:135867): user pid=50149 uid=0 auid=4294967295 ses=4294967295 msg='op=PAM:accounting acct="phxinst1" exe="/usr, /sbin/crond" hostname=? Here are some other handy grep command options you may need when searching for a text string:-c - Count the number of times a string occurs All the examples we looked at until now, we search text patterns in a single file. Understanding how to use it gives you the ability to easily find files via the terminal. To find and report toms-first-birthday.mp4 file in your HONE directory, enter: $ find $HOME -name "toms-first-birthday.mp4" -print To find and report all mp4 files starting at the /home/vivek/ directory, enter: Sometimes you remember a phrase or a given word or words, you put in a document, but you do not remember the name of the document. grep 'word' file grep 'word1 word2' file1 file2 grep [option] 'word1 word2' file1 file2. Example: grep also allows basic regular expressions for specifying patterns. Example: grep is a powerful tool for searching files in the terminal. grep -L "sl.h" *.c. This is performed using the -c (count) switch: You can do some clever things with this switch. In this tutorial we learn how to use grep command with practical examples. We also have thousands of freeCodeCamp study groups around the world. The most basic usage of the grep command is to search for a string (text) in a file. Grep can do much more than just search the contents of a specific file. 1. In this article, we'll look at how to use grep with the options available as well as basic regular expressions to search files. I want to serch for a string in all the files in the root directory. Donations to freeCodeCamp go toward our education initiatives, and help pay for servers, services, and staff. There's also a -C (--context) option which is equal to -A + -B. It can be used to find text in a file and search a directory structure of files recursively. There are more options attached to this tool. With option -o, only the matched pattern is printed line by line. For instance, to see entries in the /var/log/secure file which do not represent the word "failure" type: And then you would get results like this: Of course you can combine strings such as -v and -n: Which would show you all the non-matching entries with their associated line numbers: 1:Apr 2 03:45:07 smatteso-vm1 sshd[16278]: Connection closed by 10.1.7.101, 2:Apr 2 03:46:42 smatteso-vm1 su: pam_unix(su-l:session): session opened for user phxinst1 by (uid=0), 3:Apr 2 03:46:45 smatteso-vm1 su: pam_unix(su-l:session): session closed for user phxinst1, 4:Apr 2 03:46:45 smatteso-vm1 su: pam_unix(su-l:session): session opened for user phxinst1 by (uid=0), 5:Apr 2 03:46:48 smatteso-vm1 su: pam_unix(su-l:session): session closed for user phxinst1. -A 1 means one line after the matched line and -B 1 means one line before the matched line. To see only the messages logged at 6 a.m. The output should look something like this: Ss Mar31 0:00 /usr/bin/spice-vdagent. Ss Mar31 0:00 /usr/sbin/spice-vdagentd, root 2855 0.0 0.0 103328 888 pts/0 S+ 12:41 0:00 grep spice, gdm 5430 0.0 0.0 34488 1604 ? Just as discussed earlier, you can flip this to display the filenames which do not contain your search term(s), using the -L switch rather than -l: One especially helpful element when using grep is to comb through log files searching for messages which were logged on a certain date. This is just the basic tip of the iceberg representing the capabilities of grep. Grep can be used with any other command you like. The syntax is: Note that single or double quotes are required around the text if it is more than one word. We accomplish this by creating thousands of videos, articles, and interactive coding lessons - all freely available to the public. The -L (files without match) option does just that. It is a command line tool used in UNIX and Linux systems to search a specified pattern in a file or group of files. Add the -i switch (e.g. Here we would be taking a look on grep command in Unix with examples,Linux grep examples,grep command options,egrep command in Unix Javascript / ReactJS / NodeJS, If you read this far, tweet to the author to show them you care. After find, use a shortcut to specify the directory: "." Windows search is not without certain charms, but when I need to find files or their contents, or search for specific system information, the grep command in Linux never ceases to amaze me through its power and versatility. To do so, add the -n (number) switch: Grep would then return something like this: 1601:Apr 4 06:45:29 smatteso-vm1 sshd[14836]: pam_unix(sshd:auth): authentication failure; logname= uid=0 euid=0 tty=ssh ruser= rhost= qualys-corp.testdomain.com user=8boa5lv2rn8pso8, 1612:Apr 4 06:45:31 smatteso-vm1 sshd[14844]: pam_unix(sshd:auth): authentication failure; logname= uid=0 euid=0 tty=ssh ruser= rhost= qualys-corp.testdomain.com user=13hr26mnm8wo4k. terminal=cron res=success'. Summary: `grep -r` notes. The basic usage of grep command is to search for a specific string in the specified file as shown below. grep stands for Globally Search For Regular Expression and Print out. Note that find only looks at filenames, not contents. The best programming languages to learn--and the worst, From start to finish: How to host multiple websites on Linux with Apache, Checklist: Managing and troubleshooting iOS devices, An introduction to the Linux home directory, Comment and share: 10 ways to use grep to search files in Linux. grep all files in directory recursively. Using Grep, you can search for useful information by specifying a search criteria. find . This we called as recursive grep search. A regular expression is a string of characters that is used to specify a pattern matching rule. You can make a tax-deductible donation here. The grep filter searches a file for a particular pattern of characters, and displays all lines that contain that pattern. grep -i) to conduct a case insensitive search. Tools and tips for creating data backups on Linux servers, How to resize a virtual Red Hat Enterprise Linux partition, How to add version control for your Linux /etc directory. -exec cmd {} +: Run command cmd on a file. Basic Syntax of Grep to Find Strings/Text in Files/Directories. Let's say I want to inspect the contents of the /var/log/secure log for any instances of a failure. Notice that we also used option -n? Two … Grep can be used with any other command you like. The value passed to -C would be used for -A and -B. There are some scenarios in which you might want to do a reverse search and show results which do NOT match your input. The command used to search for files is called find.The basic syntax of the find command is as follows: find [filename]. By default, grep cannot search directories. You can search all text files in the current directory with wild cards: grep 'word-to-search' * Search sub directories recursively using grep. ; Don’t forget to list one or more directories at the end of your grep command. Scott Matteson is a senior systems administrator and freelance technical writer who also performs consulting work for small organizations. Syntax: grep "literal_string" filename $ grep "this" demo_file this line is the 1st lower case line in this file. Just add the -v switch here. … The only known post-90s systems where that's known not to work is old (very old now) GNU systems. I can narrow these down using the -m (maximum count) switch: Apr 4 06:45:29 smatteso-vm1 sshd[14836]: pam_unix(sshd:auth): authentication failure; logname= uid=0 euid=0 tty=ssh ruser= rhost= qualys-corp.testdomain.com user=8boa5lv2rn8pso8 Apr 4 06:45:31 smatteso-vm1 sshd[14844]: pam_unix(sshd:auth): authentication failure; logname= uid=0 euid=0 tty=ssh ruser= rhost= qualys-corp.testdomain.com user=13hr26mnm8wo4k. This is because it is concerned with the number of lines where the matches appear, not the number of matches. What is the grep Command? terminal=cron res=success', Apr 5 00:00:01 smatteso-vm1 audispd: node=smatteso-vm1 type=USER_ACCT msg=audit(1491364801.741:135866): user pid=50143 uid=0 auid=4294967295 ses=4294967295. Unix find command examples. For example, to display all the lines containing the string bash from the /etc/passwd file, you would run the following command: grep bash /etc/passwd. Learn some strategies for using it effectively. I love teaching what I know. Written by Guillermo Garron Date: 2011-01-25 10:36:30 00:00. You can find with man grep. But grep command in unix can also search text pattern on all files inside a given folder as well as the subfolders of that folder using -R option. © 2021 ZDNET, A RED VENTURES COMPANY. freeCodeCamp's open source curriculum has helped more than 40,000 people get jobs as developers. Get started, freeCodeCamp is a donor-supported tax-exempt 501(c)(3) nonprofit organization (United States Federal Tax Identification Number: 82-0779546). Two of them are: This pattern means that the grep will match the strings whose lines begin with the string specified after ^. To find out which C source code files contain references to the sl.h header file, use this command: grep -l "sl.h" *.c. I'm not a fan of clutter, so to get just the list of filenames which match my search (and not the contents of the files themselves) I can add the -l switch: /etc/sysconfig/network-scripts/ifcfg-eth0. Using grep you can search any string in all files available in the directory hierarchy. The name stands for Global Regular Expression Print. The options and patterns you can use with grep are varied and diverse. Linux grep command is one of the most commonly used command-line tools. If you look at the result we have above, you'll notice there are no line numbers, just the matches. The latter two have different methods for working with characters and search strings. addr=? Finally, “wc -l” count the lines in the output and prints it. In order to remember the syntax of the grep command, just remember that grep can be written as grEP which means that the expression comes before the path.. To learn more about grep, use the command "man grep" or "grep --help." Frontend Web Engineer and Technical Writer. Let's say I want to find any log files containing the word spice. This prints out the matches for the text along with the line numbers. If there is no match, no output will be printed to the terminal. You can use what's known as a recursive search to cover entire directories, subdirectories, or the entire file system and get results showing each filename that contains your search value. And of course, we can look for files that don’t contain the search term. Our mission: to help people learn to code for free. The grep command in UNIX is a command line utility for printing lines that match a pattern. Learn to code — free 3,000-hour curriculum. Using the grep Command. Example: In contrast with ^, $ specifies patterns that will be matched if the line ends with the string before $. Let's say I want to only see the first five search results. You can also use the wildcard (*) to select all files in a directory. Grep is a Unix utility that searches through either information piped to it or files in the current directory. ALL RIGHTS RESERVED. The basic grep command syntax is as follows: grep 'word' filename grep 'word' file1 file2 file3 grep 'string1 string2' filename cat otherfile | grep 'something' command | grep 'something' command option1 | grep 'data' grep --color 'data' fileName. -ls: List current file in ls -dils format on screen.-delete: Delete file. grep command to search for strings of text within files. grep comes with a lot of options which allow us to perform various search-related actions on files. When grep finds match in a line, it copies results into the screen ie stdout. If you are looking for a file that contains a certain phrase or string of characters, you can use the grep command. But grep comes with more options which help us achieve more during a search operation. You don't want to miss our tips, tutorials, and commentary on the Linux OS and open source applications. I would type: This is an example of what grep might then return: Apr 4 06:45:29 smatteso-vm1 sshd[14836]: pam_unix(sshd:auth): authentication failure; logname= uid=0 euid=0 tty=ssh ruser= rhost= qualys-corp.testdomain.com user=8boa5lv2rn8pso8 Apr 4 06:45:31 smatteso-vm1 sshd[14844]: pam_unix(sshd:auth): authentication failure; logname= uid=0 euid=0 tty=ssh ruser= rhost= qualys-corp.testdomain.com user=13hr26mnm8wo4k. Limit the list of directories to search If you don't want to search every sub-directory and just want to search directories named "dir1", "dir2", and "dir3" you can change the find command … grep command Means – globally search regular expression.It is very useful while searching for strings in Unix and Linux operating system. Grep Command in Unix with Examples. Grep is a powerful utility available by default on UNIX-based systems. A few notes about the grep -r command:. -exec grep -H “string to find” {} \; OR grep -l “string to find” `find .` OR grep -H “string to find” `find .` grep can search through your entire directory tree, scanning every file along the way: grep -r “modules” . Syntax: grep [options] [pattern] [file] The pattern is specified as a regular expression. Yes, you can apply multiple options in one command. the approaches tried are 1)grep "pattern string" this command was serching the... (3 Replies) Once again, add -i to the grep portion of the command to ignore case. This command will use find’s -exec flag to pass the found files to grep for searching. Example: By default, grep prints the line where the matched pattern is found. This is a great way to remember the grep syntax and the find syntax at the same time but the find … Before listing and detailing all the options provided by grep, let’s have a quick way to memorize the syntax of the grep command. Let's look at nine of them while applying them to the example above. You can also download a version of grep for Windows. Note that single or double quotes are required around the text if it is more than one word. In this example I'll check to see if any processes called "spice" are running: root 2179 0.0 0.0 15900 1076 ? If you try doing so, you'll get an error ("Is a directory"). This is performed using the -r switch, which I'll use to search for my user account name in the /etc directory: /etc/hosts:10.1.52.237 smatteso-vm1.dwi.testdomain.com smatteso-vm1, /etc/sysconfig/network-scripts/ifcfg-eth0:HOSTNAME="smatteso-vm1", /etc/sysconfig/rhn/systemid:smatteso-vm1.dwi.testdomain.com, /etc/sysconfig/network:HOSTNAME=smatteso-vm1. If no folder name is given, grep command will search the string inside the current working directory. Without passing any option, grep can be used to search for a pattern in a file or group of files. I can use the find command and pipe the results to grep as follows: The history file, which contains a list of recently-typed commands, is one of the best elements of Linux. A basic grep command is formatted as follows: Example: This matched pattern is on line 2. find /path/to/parent -type f -exec grep 'XXX' /dev/null {} + (the /dev/null is to make sure grep always prints a file name). Best robots at CES 2021: Humanoid hosts, AI pets, UV-C disinfecting bots, more, How to combat future cyberattacks following the SolarWinds breach, LinkedIn names the 15 hottest job categories for 2021, These are the programming languages most in-demand with companies hiring, 10 fastest-growing cybersecurity skills to learn in 2021. To grep All Files in a Directory Recursively, we need to use -R option. This works for a specific timeframe too if you add that in, of course. This particular use of the grep command doesn’t make much sense unless you use it with the -l (lowercase "L") argument as well. In a follow-up article I'll discuss some more advanced methods for using the command to get even more helpful and granular results. You will get come examples of grep command to search any string recursively in the file system. The pattern that is searched in the file is referred to as the regular expression (grep stands for globally search for regular expression and print out). Without passing any option, grep can be used to search for a pattern in a file or group of files. He resides in the Greater Boston area with his wife and three children. Use the . In the example above this would return the lowercase "failure," uppercase "FAILURE" or any combination thereof, such as "Failure.". You can also use the wildcard (*) … Linux grep command is a frequently used command by most of the Linux users. An example should help clarify things. To Search a File; To Search Multiple Files; Search All Files in Directory; To Find Whole Words Only; To Ignore Case in Grep Searches; To Search Subdirectories; Inverse grep Search; To Show Lines That Exactly Match a Search String; To List Names of Matching Files; To Count the Number of Matches $ grep -v unix examplefile.txt this is line 1 UNIX UNIX this is line 3 Unix Unix this is line 4 hello $ grep -vi unix examplefile.txt this is line 4 hello (8) Search file for multiple patterns or for patterns beginning with hyphen (-) (Linux ONLY) You may use "-e" to find multiple words or a pattern that begins with a hyphen. grep is a powerful file pattern searcher that comes equipped on every distribution of Linux.If, for whatever reason, it is not installed on your system, you can easily install it via your package manager (apt-get on Debian/Ubuntu and yum on RHEL/CentOS/Fedora).$ sudo apt-get install grep #Debian/Ubuntu With the option -w, grep ensures that the matches are exactly the same pattern as specified. By default, grep matches strings which contain the specified pattern. I'll focus on regular grep for the purpose of this article, which is intended as a beginning tutorial for this handy and reliable command. Grep (global regular expression print) command is the most powerful and regularly used Linux command-line utility. Note that if there was another 'you' on line one, option -c would still print 2. 12 Grep Command Examples. It's also possible to grep the history file for specific terms (for example, "pam_tally2") to see when they were last used and what the appropriate syntax is: 325 2017-04-06 13:50:29 pam_tally2 -u smatteso -r, 350 2017-04-06 14:05:44 history | grep pam_tally2. You can grep multiple strings in … You can use grep with "netstat" to look at listening ports, say port 22 for instance: tcp 0 0 0.0.0.0:22 0.0.0.0:* LISTEN 2154/sshd, tcp 0 0 10.1.52.237:22 10.1.13.63:51704 ESTABLISHED 40441/sshd, tcp 0 32 10.1.52.237:22 10.1.13.63:51701 ESTABLISHED 40434/sshd. Pass the -r option to grep command to search That will work on all POSIX systems including Solaris. Here are 10 examples to help sharpen your skills. The “grep -v /” command filters the output and prints only the name that doesn’t contain “/”, hence leaving out all the directories. An example should help clarify things. For instance, if I want to know how many processors are in my system I could type: It can be helpful to know which line number your search results appear on. This is really one of the most elementary uses for grep. i want the search to be limited to only the files in the directory i.e the search to be done only in the files not in the sub directory. addr=? Let's say I want to find any log files containing the word spice. You could also specify a directory in your command, but omitting it (as we did in this example) will instruct grep to search every directory in the current path.. It's a great way of merging the find and grep commands to find a text string that you know is in a file, somewhere. Grep Command The file names are listed, not the matching lines. Note there cannot be a space between "-m" and your maximum count value. Introduction. grep -R string /directory When -R options is used, The Linux grep command will search given string in the specified directory and subdirectories inside that directory. We often use it to check the number of times of a words, phrases, strings in a text file or patterns to find the number of occurrences of files with specific names under folders. With option -R, searching files within directories and subdirectories becomes possible. For example, say we have the following files (called grep.txt): The following grep command will search for all occurences of the word 'you': you is expected to have a different color than the other text to easily identify what was searched for. Delivered Tuesdays. The syntax is: grep '' . The grep command is a powerful tool for searching for files or information. addr=? Similarly, 'ou'. This means that grep yo grep.txt will print the same results as grep yo grep.txt because 'yo' can be found in you. If you would prefer to use the find command, you can use the following command syntax: $ find /path/to/search -type f -exec grep -l "your-search-string" {} \; Using the find command to search for files containing the text string. About grep, egrep ( extended grep ) and fgrep ( fixed prep ) that match a matching! Them are: this matched pattern is found ) in the current directory with wild cards grep! Directory recursively, we search text patterns in this tutorial we learn how use... The /var/log/secure log for any instances of a failure so, you can also look for string! Guillermo Garron Date: 2011-01-25 10:36:30 00:00 specified file equal to -A + -B looked at now. Specified after ^ the only known post-90s systems where that 's known not to work is old ( old... 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The -L ( files without match ) option which is equal to +... Grep command known not to work is old ( very old now ) GNU systems ( `` is senior! Wild cards: grep -r command: grep portion of the pattern is printed line by line ):... Two of them while applying them to the author to show them you.... Pattern ] [ pattern ] [ grep command to find a file in a directory ] [ pattern ] [ pattern ] file! And three children matched line and -B 1 means one line after the matched is... Match a pattern -A and -B the strings whose lines begin with the line it is more than 40,000 get. Only inside a directory '' ) screen.-delete: Delete file option which is equal to -A + -B -B means... This tutorial we learn how to use -r option them are: matched... In Unix with examples search strings the word spice this case with more options which allow us to perform search-related... Jobs as developers option -w, grep prints the line numbers information by a! / NodeJS, if you read this far, tweet to the grep command will search the string $. 34488 1604 for grep specified file as shown below 'll notice there are multiple versions of grep for.... File or group of files specific file specific timeframe too if you read this,... Man grep '' or `` grep -- help. recursively in the output should look like. Delete file ( by the line it is more than just search the contents of the basic! Consulting work for small organizations ) … grep command is to search the... Searching files in the file system fgrep ( fixed prep ) the specified file as shown.... 34488 1604 search strings while applying them to the grep filter searches file. '' demo_file this line is the most elementary uses for grep code for free it... All POSIX systems including Solaris look for a specific timeframe too if you looking... 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Msg=Audit ( 1491364801.741:135866 ): user pid=50143 uid=0 auid=4294967295 ses=4294967295 option does just that how to use option... ( files without match ) option which is equal to -A + -B printed line by.! Which contain the search term lines in the specified pattern many matches your search found `` man grep or. The screen ie stdout 5 00:00:01 smatteso-vm1 audispd: node=smatteso-vm1 type=USER_ACCT msg=audit ( 1491364801.741:135866:... Are running: root 2179 0.0 0.0 15900 1076 for grep one of the most commonly used tools... Of options which allow us to perform various search-related actions on files used command-line.! Pattern of characters that is used to find any log files containing the word spice will work all! Search term just that are running: root 2179 0.0 0.0 103328 888 pts/0 S+ 12:41 0:00 grep spice gdm... Work is old ( very old now ) GNU systems -A + -B the filenames! Resides in the file ( s ) at filenames, not contents is really one of the grep searches... Grep yo grep.txt will print the matching rules and positions, tweet to the public only... Of characters, you can customize how the tool searches for a specific process identifier the! Is: note that find only looks at filenames, not contents work for small organizations scenarios which... Option -c would still print 2 creating thousands of freeCodeCamp study groups around text! For printing lines that contain that pattern would still print 2 the tool searches for a specific in. Matches your search found messages logged at 6 a.m grep command examples are exactly the results! Tip of the iceberg representing the capabilities of grep command is one of the most usage. 'Word-To-Search ' * search sub directories recursively using grep in one command systems to search for pattern. The output should look something like this: to grep as follows: 12 grep command is search. For free command-line utility pattern grep command to find a file in a directory [ file ] the pattern ( by the line where the pattern. '' filename $ grep `` literal_string '' filename $ grep `` literal_string '' filename $ grep `` ''. Without match ) option which is equal to -A + -B specifying a search.... And subdirectories becomes possible the contents of a specific string in all the examples we looked at now! Very useful while searching for strings in Unix and Linux systems to search for given. A -c ( count ) switch: you can also look for files or information Summary... Will print the same results as grep yo grep.txt because 'yo ' can used! Before the matched pattern is specified as a regular expression print ) command is to for... You read this far, tweet to the public: note that single or double are... Stands for globally search for multiple words: grep also allows basic regular expressions for specifying patterns with -o... Into the screen ie stdout -w, grep ensures that the grep command current file in ls format! 0.0 0.0 103328 888 pts/0 S+ 12:41 0:00 grep spice, gdm 5430 0.0 0.0 103328 888 S+...