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shell stderr redirect


# redirect standard output to file 'output.txt' (overwrite existing output.txt file)
ls > output.txt
# append standard output to existing 'output.txt' (create if not exist)
ls >> output.txt

# both standard error and standard output, redirect to file
ls badfile > stdout_and_stderr.txt 2>&1
cat stdout_and_stderr.txt
ls: cannot access badfile: No such file or directory
 2>&1 redirects stderr to stdout

# pipe: past both standard error and output to a pipe
ls badfile 2>&1 | grep 'cannot access'
ls: cannot access badfile: No such file or directory