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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 DEBIAN

i-ls

i-ls(1) 						      General Commands Manual							   i-ls(1)

NAME

       i-ls - display file stat and checksum information for files

SYNOPSIS

       i-ls [-s] filename

       i-ls [-s] dirname

       Specify a filename for i-ls to examine, or specify a directory with dirname to examine all the files in the directory.

       -s

	      Do not show/calculate checksums for all regular files.

DESCRIPTION

       The integrit system detects intrusion by detecting when trusted files have been altered.

       integrit records information about files in a database.	i-ls allows the user to see that information for live files.

       The output syntax is the same as that of integrit.

EXAMPLES

	    i-ls /tmp/foo.txt

       shows file stat attributes for the file, "/tmp/foo.txt".

	    i-ls /tmp

       shows file stat attributes for all files in the directory, "/tmp".

	    i-ls -s /tmp

       shows file stat attributes for all files in the directory, "/tmp", also including also checksums for all regular files.

AUTHOR

       Ed L Cashin <ecashin@users.sourceforge.net>

       See the integrit web site for up to date releases and information at

	   http://integrit.sourceforge.net/

SEE ALSO

       Integrit File Verification System Manual (info), lstat(2)

Version 4.1							   Jul 27, 2001 							   i-ls(1)
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