![]() In the section "String constants"), but should in general be avoided since when trying to port the regex to other programs/environments it may get a special meaning there (in vim, \= actually is a regex quantifier), or even within the same program in a future version. This may work in many cases (the GNU awk man-page e.g. You have escaped several characters that actually don't have a special meaning in (most implementations of) regular expressions, e.g. If the program you use supports them, character classes may be a "safer", but as stated, not necessarily portable, way to express that kind of specification (the intention behind your use of would be fulfilled with the ] POSIX character class, for example). ![]() xXyYz, so this needs to be used with care (see here and here for further discussions on the subject). The "naive" interpretation that means abcdefgh.xyz is only true in the C locale in others it often means aAbBcCdD. The meaning of range specifications in character lists (such as ) can depend on the locale settings, specifically the collation order. is a Perl extension to regular expressions, and is not necesserily portable across programs designed to handle regular expressions. to only print the filenames (which makes for cleaner output if many files match).Īs correctly noted by Stéphane Chazelas, and as reference for possible future readers: several elements of your syntax are non-portable extensions to the regular expression syntax, and the behavior of other constructs may vary depending on the environment settings:Ĭharacter classes (not to be confused with character lists) are extensions to the standard ERE. Where the -H option to grep will ensure the filename is printed, too. The regular expressions that I use to find the string is: \$ \ For example, for ad-hoc (but unindexed) greps through header files: find ~ -follow -type f -name \*.h | xargs grep -nH "identifier"Īnd one final extension, to make that last command work properly if you have files & directories with spaces in them: find ~ -follow -type f -name \*.I like to search all PHP files and find a particular string that is identified by a regular expression. it's often faster to let the xargs command pass your found files as arguments to another command, all at once or big chunks at a time. The latter runs a command on each file at a time, though. tack on > filename at the end), or use the -exec option to run a command (see the man page for details). To do something with the files you found: you can dump this to a file using stdout redirection (e.g. To make sure find follows symbolic links (I usually want to do this myself when doing searches): find ~ -follow -type f -iname \*.pdf To prune the results to files only (the name expression will probably take care of this for you, but just in case you have any weirdly-named directories): find ~ -type f -iname \*.pdf It will not only tell you which files differ, but also how they differ. It can compare two tarballs, ISO images, or PDF just as easily. touch -t 201112220000 start touch -t 201112240000 stop find. I especially like about it that it can diff into files: It will recursively unpack archives of many kinds and transform various binary formats into more human readable form to compare them. The easiest way to specify a date range with find is to create files at the boundaries of the range and use the -newer predicate. To find case-insensitively: find ~ -iname \*.pdf Generally speaking, when you're looking for files in a directory and its subdirectories recursively, use find. Using '*.pdf' and "*.pdf" will have the same effect as \*.pdf. Note that the wildcard * has to be escaped so that the shell doesn't interpret it before find gets its hands on it. To find in home directory by name: find ~ -name \*.pdf You're simply missing the predicate that says what you're searching by (e.g.
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