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Full Discussion: Help understanding a simple command in BASH
Top Forums UNIX for Dummies Questions & Answers Help understanding a simple command in BASH Post 302502028 by phunkypants on Sunday 6th of March 2011 03:29:44 PM
Old 03-06-2011
Help understanding a simple command in BASH
This is the command. Assume file1 exists but file2 does not:
ls file1 file2 >newfile 2>&1

This simply makes a text file with two lines: file1 \n file2 could not be found. What I don't understand is that when you run this command: ls file1 file2 >newfile, it prints "file2 could not be found" to the screen but stores "file1" in newfile. So my question is what exactly does 2>&1 do and how does this explain the difference between these two commands:
ls file1 file2 >newfile 2>&1
ls file1 file2 >newfile
 

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LEARN ABOUT SUSE

lzcmp

XZDIFF(1)							     XZ Utils								 XZDIFF(1)

NAME

       xzcmp, xzdiff, lzcmp, lzdiff - compare compressed files

SYNOPSIS

       xzcmp [cmp_options] file1 [file2]
       xzdiff [diff_options] file1 [file2]
       lzcmp [cmp_options] file1 [file2]
       lzdiff [diff_options] file1 [file2]

DESCRIPTION

       xzcmp  and  xdiff invoke cmp(1) or diff(1) on files compressed with xz(1), lzma(1), gzip(1), or bzip2(1).  All options specified are passed
       directly to cmp or diff.  If only one file is specified, then the files compared are file1 (which must have a suffix of	a  supported  com-
       pression  format)  and  file1 from which the compression format suffix has been stripped.  If two files are specified, then they are uncom-
       pressed if necessary and fed to cmp(1) or diff(1).  The exit status from cmp or diff is preserved.

       The names lzcmp and lzdiff are provided for backward compatibility with LZMA Utils.

SEE ALSO

       cmp(1), diff(1), xz(1), gzip(1), bzip2(1), zdiff(1)

BUGS

       Messages from the cmp(1) or diff(1) programs refer to temporary filenames instead of those specified.

Tukaani 							    2009-07-05								 XZDIFF(1)
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