This post will guide you how to search for pattern in given files and only display the file name when lines matching the pattern from the command line in your Linux opearting systems. How do I use the grep command to searching a patter from the specified files or directory and only display the file name when mathcing pattern.
Grep Command
Grep searches for PATTERN in each FILE. A FILE of “-” stands for standard input. If no FILE is given, recursive searches examine the working directory, and nonrecursive searches read standard input. By default, grep prints the matching lines.
The syntax of the grep command is as followss:
grep [OPTIONS] PATTERN [FILE...] grep [OPTIONS] -e PATTERN ... [FILE...] grep [OPTIONS] -f FILE ... [FILE...]
For example, you want to find a pattern “root” from two given files “/etc/passwd” and “/etc/group” with grep command, just type:
$ grep "root" /etc/passwd /etc/group
outputs:
[root@localhost ~]# grep "root" /etc/passwd /etc/group /etc/passwd:root:x:0:0:root:/root:/bin/bash /etc/passwd:operator:x:11:0:operator:/root:/sbin/nologin /etc/group:root:x:0:
Form the above outputs, you should know that the first field is the file name that contains the mathcing line.
Only Dispaly File Names When Matching
If you only want to dispaly file names when using grep command to searching mathcing lines from the given files or directories in your Linux system, and you need to pass the “-l ” option to the grep command, type:
$ grep -l "pattern" fileNames $ grep -l "root" /etc/passwd /etc/group
outputs:
[root@localhost ~]# grep -l "root" /etc/passwd /etc/group
/etc/passwd
/etc/group
If you want to add prefix in each line of output with the 1-based line number within its input file when using grep command, and you need to pass the -n or –line-number option to the grep command, type:
$ grep -n "root" /etc/passwd /etc/group
outputs:
[root@localhost ~]# grep -n "root" /etc/passwd /etc/group
/etc/passwd:1:root:x:0:0:root:/root:/bin/bash
/etc/passwd:10:operator:x:11:0:operator:/root:/sbin/nologin
/etc/group:1:root:x:0:
Let’s see the second field from the above outputs, and it indicates the line number of matching line within its input file (/etc/passwd, or /etc/group).
If you want to get more detailed usage info about the grep command, and you can pass the “–help” option to the grep command to output a useage message, type:
$ grep --help
Outputs:
[root@localhost ~]# grep --help
Usage: grep [OPTION]... PATTERN [FILE]...
Search for PATTERN in each FILE.
Example: grep -i 'hello world' menu.h main.c
Pattern selection and interpretation:
-E, --extended-regexp PATTERN is an extended regular expression
-F, --fixed-strings PATTERN is a set of newline-separated strings
-G, --basic-regexp PATTERN is a basic regular expression (default)
-P, --perl-regexp PATTERN is a Perl regular expression
-e, --regexp=PATTERN use PATTERN for matching
-f, --file=FILE obtain PATTERN from FILE
-i, --ignore-case ignore case distinctions
-w, --word-regexp force PATTERN to match only whole words
-x, --line-regexp force PATTERN to match only whole lines
-z, --null-data a data line ends in 0 byte, not newline
Miscellaneous:
-s, --no-messages suppress error messages
-v, --invert-match select non-matching lines
-V, --version display version information and exit
--help display this help text and exit
Output control:
-m, --max-count=NUM stop after NUM selected lines
-b, --byte-offset print the byte offset with output lines
-n, --line-number print line number with output lines
--line-buffered flush output on every line
-H, --with-filename print file name with output lines
-h, --no-filename suppress the file name prefix on output
--label=LABEL use LABEL as the standard input file name prefix
-o, --only-matching show only the part of a line matching PATTERN
-q, --quiet, --silent suppress all normal output
--binary-files=TYPE assume that binary files are TYPE;
TYPE is 'binary', 'text', or 'without-match'
-a, --text equivalent to --binary-files=text
-I equivalent to --binary-files=without-match
-d, --directories=ACTION how to handle directories;
ACTION is 'read', 'recurse', or 'skip'
-D, --devices=ACTION how to handle devices, FIFOs and sockets;
ACTION is 'read' or 'skip'
-r, --recursive like --directories=recurse
-R, --dereference-recursive
likewise, but follow all symlinks
--include=FILE_PATTERN
search only files that match FILE_PATTERN
--exclude=FILE_PATTERN
skip files and directories matching FILE_PATTERN
--exclude-from=FILE skip files matching any file pattern from FILE
--exclude-dir=PATTERN directories that match PATTERN will be skipped.
-L, --files-without-match print only names of FILEs with no selected lines
-l, --files-with-matches print only names of FILEs with selected lines
-c, --count print only a count of selected lines per FILE
-T, --initial-tab make tabs line up (if needed)
-Z, --null print 0 byte after FILE name
Context control:
-B, --before-context=NUM print NUM lines of leading context
-A, --after-context=NUM print NUM lines of trailing context
-C, --context=NUM print NUM lines of output context
-NUM same as --context=NUM
--group-separator=SEP use SEP as a group separator
--no-group-separator use empty string as a group separator
--color[=WHEN],
--colour[=WHEN] use markers to highlight the matching strings;
WHEN is 'always', 'never', or 'auto'
-U, --binary do not strip CR characters at EOL (MSDOS/Windows)
When FILE is '-', read standard input. With no FILE, read '.' if
recursive, '-' otherwise. With fewer than two FILEs, assume -h.
Exit status is 0 if any line is selected, 1 otherwise;
if any error occurs and -q is not given, the exit status is 2.
Report bugs to: bug-grep@gnu.org
GNU grep home page: <http://www.gnu.org/software/grep/>
General help using GNU software: <http://www.gnu.org/gethelp/>
Conclusion
You should know that how to display file names only when mathcing pattern with grep command from the command line in your Linux system.