How do I grep multiple patterns in Unix?

Can you grep for multiple patterns in a file?

By using the grep command, you can customize how the tool searches for a pattern or multiple patterns in this case. You can grep multiple strings in different files and directories. The tool prints all lines that contain the words you specify as a search pattern.

How do I combine two grep commands?

Use a single arrow the first time and double arrows subsequent times to append to the file. The first two grep commands print just the line with the match and the last one prints the line and one line after.

How do you grep multiple lines after a match?

To also show you the lines before your matches, you can add -B to your grep. The -B 4 tells grep to also show the 4 lines before the match. Alternatively, to show the log lines that match after the keyword, use the -A parameter. In this example, it will tell grep to also show the 2 lines after the match.

How do you find a pattern in all files in UNIX using grep?

The grep command searches through the file, looking for matches to the pattern specified. To use it type grep , then the pattern we’re searching for and finally the name of the file (or files) we’re searching in. The output is the three lines in the file that contain the letters ‘not’.

What patterns does grep let you use?

GNU grep supports three regular expression syntaxes, Basic, Extended, and Perl-compatible. In its simplest form, when no regular expression type is given, grep interpret search patterns as basic regular expressions. To interpret the pattern as an extended regular expression, use the -E ( or –extended-regexp ) option.

How do I grep a word in multiple files in Linux?

To search multiple files with the grep command, insert the filenames you want to search, separated with a space character. The terminal prints the name of every file that contains the matching lines, and the actual lines that include the required string of characters. You can append as many filenames as needed.

How do you grep for not matching?

Using Grep to invert Output

The -v option instructs grep to print all lines that do not contain or match the expression. The –v option tells grep to invert its output, meaning that instead of printing matching lines, do the opposite and print all of the lines that don’t match the expression.

How do you grep with and condition?

Grep OR Operator

1. Grep OR Using | If you use the grep command without any option, you need to use | to separate multiple patterns for the or condition. …
2. Grep OR Using -E. grep -E option is for extended regexp. …
3. Grep OR Using egrep. egrep is exactly same as ‘grep -E’. …
4. Grep OR Using grep -e.

21 окт. 2011 г.

How do you use Egrep?

It treats the pattern as an extended regular expression and prints out the lines that match the pattern. If there are several files with the matching pattern, it also displays the file names for each line. Example: Note: The egrep command used mainly due to the fact that it is faster than the grep command.

How do you get 10 lines before and after grep?

4 Answers. You can use the -B and -A to print lines before and after the match. Will print the 10 lines before the match, including the matching line itself. And if you need to print 10 lines of leading and trailing output context.

How do you grep the first 10 lines?

head -n10 filename | grep … head will output the first 10 lines (using the -n option), and then you can pipe that output to grep . You can use the following line: head -n 10 /path/to/file | grep […]

What options can be used with grep command?

Command-line options aka switches of grep:

• -e pattern.
• -i: Ignore uppercase vs. …
• -v: Invert match.
• -c: Output count of matching lines only.
• -l: Output matching files only.
• -n: Precede each matching line with a line number.
• -b: A historical curiosity: precede each matching line with a block number.

Why does grep take so long?

There are many reasons why your process could be slow, heavy load on the disk, a slow nfs if you use it, extremely long lines to parse, … without more information on the input file and the system you are running this on, it is hard to say why it is so slow.

How do you grep a specific line?

The following command will do what you asked for “extract the lines between 1234 and 5555” in someFile. You don’t need to run grep followed by sed . which deletes all lines from the first matched line to the last match, including those lines. Use sed -n with “p” instead of “d” to print those lines instead.

What is grep command?

grep is a command-line utility for searching plain-text data sets for lines that match a regular expression. Its name comes from the ed command g/re/p (globally search for a regular expression and print matching lines), which has the same effect.