How to use -prune option of find in sh

Question

I don t quite understand the example given from the man find  can anyone give me some examples and explanations  Can I combine regular expression in it      The more detailed question is like this    Write a shell script  changeall  which has an interface like changeall  -r -R   string1   string2   It will find all files with an suffix of  h   C   cc  or  cpp and change all occurrences of string1 to string2  -r is option for staying in current dir only or including subdir s   NOTE     For non-recursive case  ls is NOT allowed  we could only use find and sed  I tried find -depth but it was NOT supported  That s why I was wondering if -prune could help  but didn t understand the example from man find       EDIT2  I was doing assignment  I didn t ask question in great details because I would like to finish it myself  Since I already done it and hand it in  now I can state the whole question  Also  I managed to finish the assignment without using -prune  but would like to learn it anyway

User · Answer

If you read all the good answers here my understanding now is that the following all return the same results:

find . -path ./dir1\*  -prune -o -print

find . -path ./dir1  -prune -o -print

find . -path ./dir1\*  -o -print
#look no prune at all!

But the last one will take a lot longer as it still searches out everything in dir1. I guess the real question is how to -or out unwanted results without actually searching them.

So I guess prune means don't decent past matches but mark it as done...

http://www.gnu.org/software/findutils/manual/html_mono/find.html "This however is not due to the effect of the ‘-prune’ action (which only prevents further descent, it doesn't make sure we ignore that item). Instead, this effect is due to the use of ‘-o’. Since the left hand side of the “or” condition has succeeded for ./src/emacs, it is not necessary to evaluate the right-hand-side (‘-print’) at all for this particular file."

User · Answer

Prune is a do not recurse at any directory switch   From the man page     If -depth is not given  true           if the file is a directory  do not descend into it      If -depth is given  false  no effect    Basically it will not desend into any sub directories   Take this example   You have the following directories    home test2  home test2 test2   If you run find -name test2   It will return both directories  If you run find -name test2 -prune   It will return only  home test2 as it will not descend into  home test2 to find  home test2 test2

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Adding to the advice given in other answers  I have no rep to create replies      When combining -prune with other expressions  there is a subtle difference in behavior depending on which other expressions are used    Laurence Gonsalves  example will find the    foo  files that aren t under   snapshot  directories -  find   -name  snapshot -prune -o -name    foo  -print   However  this slightly different short-hand will  perhaps inadvertently  also list the  snapshot directory  and any nested  snapshot directories  -  find   -name  snapshot -prune -o -name    foo    The reason is  according to the manpage on my system  -     If the given expression does not contain any of the primaries -exec    -ls  -ok  or -print  the given expression is effectively replaced by         given expression   -print   That is  the second example is the equivalent of entering the following  thereby modifying the grouping of terms -  find      -name  snapshot -prune -o -name    foo     -print   This has at least been seen on Solaris 5 10  Having used various flavors of  nix for approx 10 years  I ve only recently searched for a reason why this occurs

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The thing I d found confusing about -prune is that it s an action  like -print   not a test  like -name   It alters the  quot to-do quot  list  but always returns true  The general pattern for using -prune is this  find  path   conditions to prune  -prune -o                your usual conditions   actions to perform   You pretty much always want the -o  logical OR  immediately after -prune  because that first part of the test  up to and including -prune  will return false for the stuff you actually want  ie  the stuff you don t want to prune out   Here s an example  find   -name  snapshot -prune -o -name    foo  -print  This will find the  quot   foo quot  files that aren t under  quot  snapshot quot  directories  In this example  -name  snapshot makes up the  conditions to prune   and -name    foo  -print is  your usual conditions  and  actions to perform   Important notes   If all you want to do is print the results you might be used to leaving out the -print action  You generally don t want to do that when using -prune  The default behavior of find is to  quot and quot  the entire expression with the -print action if there are no actions other than -prune  ironically  at the end  That means that writing this   find   -name  snapshot -prune -o -name    foo                 DON T DO THIS  is equivalent to writing this   find      -name  snapshot -prune -o -name    foo     -print   DON T DO THIS  which means that it ll also print out the name of the directory you re pruning  which usually isn t what you want  Instead it s better to explicitly specify the -print action if that s what you want   find   -name  snapshot -prune -o -name    foo  -print         DO THIS   If your  quot usual condition quot  happens to match files that also match your prune condition  those files will not be included in the output  The way to fix this is to add a -type d predicate to your prune condition  For example  suppose we wanted to prune out any directory that started with  git  this is admittedly somewhat contrived -- normally you only need to remove the thing named exactly  git   but other than that wanted to see all files  including files like  gitignore  You might try this  find   -name   git   -prune -o -type f -print                 DON T DO THIS  This would not include  gitignore in the output  Here s the fixed version  find   -name   git   -type d -prune -o -type f -print         DO THIS    Extra tip  if you re using the GNU version of find  the texinfo page for find has a more detailed explanation than its manpage  as is true for most GNU utilities

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find builds a list of files  It applies the predicate you supplied to each one and returns those that pass   This idea that -prune means exclude from results was really confusing for me  You can exclude a file without prune   find -name  bad guy  -o -name  good guy  -print     good guy   All -prune does is alter the behavior of the search  If the current match is a directory  it says  hey find  that file you just matched  dont descend into it   It just removes that tree  but not the file itself  from the list of files to search   It should be named -dont-descend

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There are quite a few answers  some of them are a bit too much theory-heavy  I ll leave why I needed prune once so maybe the need-first example kind of explanation is useful to someone    Problem I had a folder with about 20 node directories  each having its node modules directory as expected  Once you get into any project  you see each    node modules module  But you know how it is  Almost every module has dependencies  so what you are looking at is more like projectN node modules moduleX node modules moduleZ    I didn t want to drown with a list with the dependency of the dependency of    Knowing -d n   -depth n  it wouldn t have helped me  as the main first node modules directory I wanted of each project was at a different depth  like this  Projects MysuperProjectName project node modules     Projects Whatshisname version3 project node modules     Projects project node modules     Projects MysuperProjectName testProject november2015Copy project node modules            How can I get the first a list of paths ending at the first node modules and move to the next project to get the same  Enter -prune When you add -prune  you ll still have a standard recursive search  Each  quot path quot  is analyzed  and every find gets spit out and find keeps digging down like a good chap  But it s the digging down for more node modules what I didn t want  So  the difference is that in any of those different paths  -prune will find to stop digging further down that particular avenue when it has found your item  In my case  the node modules folder

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Beware that -prune does not prevent descending into any directory as some have said  It prevents descending into directories that match the test it s applied to  Perhaps some examples will help  see the bottom for a regex example   Sorry for this being so lengthy     find   -printf   y  p n       print the file type the first time FYI d   f   test d   dir1 d   dir1 test f   dir1 test file f   dir1 test test d   dir1 scripts f   dir1 scripts myscript pl f   dir1 scripts myscript sh f   dir1 scripts myscript py d   dir2 d   dir2 test f   dir2 test file f   dir2 test myscript pl f   dir2 test myscript sh    find   -name test   test   dir1 test   dir1 test test   dir2 test    find   -prune      find   -name test -prune   test   dir1 test   dir2 test    find   -name test -prune -o -print     dir1   dir1 scripts   dir1 scripts myscript pl   dir1 scripts myscript sh   dir1 scripts myscript py   dir2    find   -regex     my  p      dir1 scripts myscript pl   dir1 scripts myscript py   dir2 test myscript pl    find   -name test -prune -regex     my  p     no results     find   -name test -prune -o -regex     my  p      test   dir1 test   dir1 scripts myscript pl   dir1 scripts myscript py   dir2 test    find   -regex     my  p    -a -not -regex    test      dir1 scripts myscript pl   dir1 scripts myscript py    find   -not -regex    test                          dir1   dir1 scripts   dir1 scripts myscript pl   dir1 scripts myscript sh   dir1 scripts myscript py   dir2

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Normally the native way we do things in linux and the way we think is from left to right  So you would go and write what you are looking for first   find   -name    php    Then you probably hit enter and realize you are getting too many files from directories you wish not to  Let s exclude  media to avoid searching your mounted drives  You should now just APPEND the following to the previous command   -print -o -path   media  -prune   so the final command is   find   -name    php  -print -o -path   media  -prune                    lt --- Include ---                        lt ---------- Exclude ---------    I think this structure is much easier and correlates to the right approach

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I am no expert at this  and this page was very helpful along with http   mywiki wooledge org UsingFind   Just noticed -path is for a path that fully matches the string path that comes just after find    in theses examples  where as -name matches all basenames   find   -path    git  -prune -o -name file  -print   blocks the  git directory in your current directory   as your finding in      find   -name  git  -prune -o -name file  -print   blocks all  git subdirectories recursively   Note  the     is extremely important    -path must match a path anchored to   or whatever comes just after find if you  get matches with out it  from the other side of the or  -o   there probably not being pruned  I was naively unaware of this and it put me of using -path when it is great when you don t want to prune all subdirectory with the same basename  D

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Show everything including dir itself but not its long boring contents   find   -print -name dir -prune

[regex] How to use '-prune' option of 'find' in sh?

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