![]() You can grep multiple strings in different files and directories. The canonical use of grep is searching for a precise string of characters in some greater body of text, and returning the line or lines containing successful matches. By using the grep command, you can customize how the tool searches for a pattern or multiple patterns in this case. The name stands for Global Regular Expression Print. In this case, 'pgrep' won't be reliable (if usable at all) for identifying the exact process you need. Grep is a powerful utility available by default on UNIX-based systems. Imagine a machine where several Tomcat instances are running with processes like: tomcat 154304 1 8 10:43 ? 00:00:59 /usr/lib/jvm/jre/bin/java .file=/somewhere/conf/logging.properties =true =file:/dev/./urandom =2048 = .SecurityListener.UMASK=0027 -Xms512M -Xmx1024M -server -XX:+UseParallelGC = -classpath. ![]() By default, grep displays the matched lines, and it can be used to search for lines of text that match one or more regular expressions, and it outputs only the matched lines. Grep Regex Example Run the following command to test how grep regex works: grep if. The grep command is primarily used to search a text or file for lines that contain a match to the specified words/strings. ![]() Pearl Compatible Regular Expressions ( PCRE) By default, grep uses the BRE syntax. grep understands three different versions of regular expression syntax: basic (BRE), extended (ERE) and perl (PCRE). This make the solution more reliable than the one that 'pgrep' offers returning just a PID The grep command offers three regex syntax options: 1. When grep stops after NUM matching lines, it outputs any trailing context lines. *) # other UNIX flavors get a minimalist version.įor a 'fnord' both the regular expression nord or pgrep usage may work.īut for a generic use, the regex is by far more flexible, allowing to get more information on the output in case you need to refine the search. This enables a calling process to resume a search. The simplest shell-agnostic way to do this would be to store it in a variable first: PS_OUTPUT="$(ps aux)" echo "$PS_OUTPUT" |grep fnordįrom my rc files, I have a case-insensitive version that takes grep's options: psl() ![]()
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