This can be done using xargs, which is a tool to read items from the standard input. This enables a calling process to resume a search. We can force grep to only display matches that are either at the start or the end of a line. In this article, we will show you several ways to check if a string contains a substring. When the -v or --invert-match option is also used, grep stops after outputting NUM non-matching lines. ./grep.bash: line 27: =: command not found Perhaps when it could not find the element in the file, the "K= " is treated as return status as well which … – Gonzalo Matheu Aug 24 '17 at 14:59 And of course, we can look for files that don’t contain the search term. If TYPE is text, grep processes a binary file as if it were text; this is equivalent to the -a option. When grep stops after NUM matching lines, it outputs any trailing context lines. This is the wage list of Manchester United Football Team. The -q option tells grep to be quiet, to omit the output. When I execute ls /directory | grep '[^term]' in Bash I get a regular listing, as if the grep command is ignored somehow. Additionally, you will need to direct the output of the first grep to the second as command line arguments. If TYPE is without-match, when grep discovers null input binary data it assumes that the rest of the file does not match; this is equivalent to the -I option. One of the most common operations when working with strings in Bash is to determine whether or not a string contains another string. As you observe, it did filtered the output by removing non-relevant match although the grep was not 100% successful. We have all ready provided tutorial and examples about grep and egrep.In this tutorial we will look grep command or, and, not logic operations in detail.. I would change the title of the question with what you want to achieve (i.e: execute a command depending on the status of a service), instead of how you thought you can do it (i.e: evaluating grep result). I want to run DDNS that updates from the my server running Ubuntu 14.04. Just as -L searches for contents of a file without a match, -l searches for the contents of a file with a match.. From the man page of grep : -w, --word-regexp Select only those lines containing matches that form whole words. Example Text. We will use following text during tutorial for grep operations. logrep is very useful tool for text search and pattern matching. Start and End of Lines. I tried the same thing with egrep, I tried to use it with double and single quotes, but to no better results.When I try ls /directory | grep '^[term] I get all entries beginning with term - as expected.. set -e or set -o errexit. I'm still very new to scripting in bash, and just trying a few what I thought would be basic things. The file names are listed, not the matching lines. `fgrep' means `grep -F'. So you will need to specify the -l flag in the second "grepping.". The -L (files without match) option does just that. grep -L "sl.h" *.c. Exit immediately if a pipeline (which may consist of a single simple command), a list, or a compound command (see SHELL GRAMMAR above), exits with a non-zero status. grep searches the named input FILEs (or standard input if no files are named, or if a single hyphen-minus (-) is given as file name) for lines containing a match to the given PATTERN.By default, grep prints the matching lines. If less than two FILEs given, assume -h. Exit status is 0 if match, 1 if no match, and 2 if trouble. As the answer states, grep is not required. With no FILE, or when FILE is -, read standard input. Solution #!/bin/bash -e echo "before" echo "anything" | grep e || : # it would if I searched for 'y' instead echo "after" exit Explanation. -U, --binary do not strip CR characters at EOL (MSDOS) -u, --unix-byte-offsets report offsets as if CRs were not there (MSDOS) `egrep' means `grep -E'. 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