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.

2019年5月16日 · 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.

2016年7月6日 · 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.

2010年1月1日 · 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).

2010年11月8日 · 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 .

2015年1月5日 · 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.

2011年12月1日 · 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 ...

In GNU grep, there is no difference in available functionality between basic and extended syntaxes. In other implementations, basic regular expressions are less powerful. The following description applies to extended regular expressions; differences for basic regular expressions are summarized afterwards.

2010年4月22日 · you can use grep incase you are not keen in the sequence of the pattern. grep -l "pattern1" filepattern*.* | xargs grep "pattern2" example. grep -l "vector" *.cpp | xargs grep "map" grep -l will find all the files which matches the first pattern, and xargs will grep for the second pattern. Hope this helps.

2016年3月25日 · For potentially gzip-compressed files, you can use zgrep which is generally a shell script wrapper around grep, and use one of the grep solutions above (not the ast-open one as that grep implementation cannot be use by zgrep) or you could use the PerlIO::gzip module of perl which can transparently uncompress files upon input: