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Full Discussion: For loop without checking file exists
Top Forums Shell Programming and Scripting For loop without checking file exists Post 302971380 by migurus on Tuesday 19th of April 2016 02:37:40 PM
Old 04-19-2016
For loop without checking file exists
In several scripts that process files matched by name pattern I needed to add a check for file existence. Just to illustrate let's say I need to process all N??? files:
Code:
/tmp$ touch N100 N101
/tmp$ l ?10[01]
-rw-rw-r--   1 moss     group          0 Apr 19 11:22 N100
-rw-rw-r--   1 moss     group          0 Apr 19 11:22 N101
/tmp$ for fn in N???; do echo $fn; ls -l $fn; done
N100
-rw-rw-r--   1 moss     group          0 Apr 19 11:22 N100
N101
-rw-rw-r--   1 moss     group          0 Apr 19 11:22 N101

If there is no N files, this for loop would try to execute ls with non-existent pattern:
Code:
/tmp$ rm N???
/tmp$ for fn in N???; do echo $fn; ls -l $fn; done              
N???
ls: N??? not found: No such file or directory (error 2)

To avoid running a process against non-existent file I add if file exists check:
Code:
/tmp$ for fn in N???; do if [ -f $fn ]; then ls -l $fn; fi; done
/tmp$

Is there any way in shell to not use those file exists checks and still run process only for an exisant file?
 

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LEARN ABOUT NETBSD

dh_movefiles

DH_MOVEFILES(1) 						     Debhelper							   DH_MOVEFILES(1)

NAME

       dh_movefiles - move files out of debian/tmp into subpackages

SYNOPSIS

       dh_movefiles [debhelperoptions] [--sourcedir=dir] [-Xitem] [file...]

DESCRIPTION

       dh_movefiles is a debhelper program that is responsible for moving files out of debian/tmp or some other directory and into other package
       build directories. This may be useful if your package has a Makefile that installs everything into debian/tmp, and you need to break that
       up into subpackages.

       Note: dh_install is a much better program, and you are recommended to use it instead of dh_movefiles.

FILES

       debian/package.files
	   Lists the files to be moved into a package, separated by whitespace. The filenames listed should be relative to debian/tmp/. You can
	   also list directory names, and the whole directory will be moved.

OPTIONS

       --sourcedir=dir
	   Instead of moving files out of debian/tmp (the default), this option makes it move files out of some other directory. Since the entire
	   contents of the sourcedir is moved, specifying something like --sourcedir=/ is very unsafe, so to prevent mistakes, the sourcedir must
	   be a relative filename; it cannot begin with a `/'.

       -Xitem, --exclude=item
	   Exclude files that contain item anywhere in their filename from being installed.

       file ...
	   Lists files to move. The filenames listed should be relative to debian/tmp/. You can also list directory names, and the whole directory
	   will be moved. It is an error to list files here unless you use -p, -i, or -a to tell dh_movefiles which subpackage to put them in.

NOTES

       Note that files are always moved out of debian/tmp by default (even if you have instructed debhelper to use a compatibility level higher
       than one, which does not otherwise use debian/tmp for anything at all). The idea behind this is that the package that is being built can be
       told to install into debian/tmp, and then files can be moved by dh_movefiles from that directory. Any files or directories that remain are
       ignored, and get deleted by dh_clean later.

SEE ALSO

       debhelper(7)

       This program is a part of debhelper.

AUTHOR

       Joey Hess <joeyh@debian.org>

11.1.6ubuntu2							    2018-05-10							   DH_MOVEFILES(1)
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