I am trying to understand the difference between grep -e and grep -E. Now from grep manpage I got:-E, --extended-regexp. Interpret PATTERN as an extended regular expression (see below).-e PATTERN, --regexp=PATTERN. Use PATTERN as the pattern; useful to protect patterns beginning with - The above explanation does not make sense for me.

Jul 6, 2016 · grep '*abc*' file2 This one return *abc, because there is a * in the front, it matches the pattern *abc*. (3) grep '*abc*' file3 This one return *abcc because there is a * in the front and 2 c at the tail. so it matches the pattern *abc* (4) grep '.*abc.*' file1 This one return abc because .* indicate 0 or more repetition of any character.

May 16, 2019 · Here's an example of grep -q: scanning the output of a command for a particular value, then performing an action if the value is found: if docker context ls | grep -q dm-manager; then docker context rm dm-manager fi If the list of docker contexts contains dm-manager then remove docker context dm-manager.

Feb 16, 2016 · Recursive grep is, of course, still preferable if available, but there's little reason to avoid the xargs recipe (do use -H for the grep to avoid the final invocation of grep getting passed only a single filename, though).

Nov 8, 2010 · grep -nr 'yourString*' . The dot at the end searches the current directory. Meaning for each parameter:-n Show relative line number in the file 'yourString*' String for search, followed by a wildcard character -r Recursively search subdirectories listed .

Jan 5, 2015 · There are lot of ways to use grep with logical operators. Using multiple -e options matches anything that matches any of the patterns, giving the OR operation. Example: grep -e pattern1 -e pattern2 filename. In extended regular expressions (grep -E), you can use | to combine multiple patterns with the OR operation.

Sep 20, 2015 · Generate a list with the result of the first grep: grep pattern | awk -F':' '{print $1}' Second grep into the list of files like here. xargs grep -i pattern. apply this cascading filter the times you need just adding awk to get only the filenames and xargs to pass the filenames to grep -i. For example:

grep --color 'pattern\|$' file grep --color -E 'pattern|$' file egrep --color 'pattern|$' file The | symbol is the OR operator. Either escape it using \ or tell grep that the search text has to be interpreted as regular expressions by adding -E or using the egrep command instead of grep .

grep -v is your friend: grep --help | grep invert -v, --invert-match select non-matching lines. Also check out the related -L (the complement of -l).-L, --files-without-match only print FILE names containing no match

Dec 1, 2011 · The grep utility looks for patterns inside files; it's irrelevant if what you care about is the file's name. Shell wildcard patterns are the way to match files by their names. In modern shells, wildcard patterns have the same expressive power as regular expressions (i.e. what you can do with one, you can do with the other), but they have a ...