Shell Script Usage Tips 2

0--stdin Standard input

1--stdout Standard Output

2--stderr standard Error

redirect

echo "This was a good idea" > Temp.txt

Temp.txt content will be emptied first before entering "this is a good idea"

Additional

echo "This was a bad idea" >> temp.txt

Cat Temp.txt

Print exit Status: Echo $?

LS + 2>out.txt

2 input error, output to OUT.txt

CMD 2>stderr.txt 1>stdout.txt

Correct output to Stdout.txt, error output to stderr.txt;

Redirect to the same file:

CMD 2>&1 output.txt

Tee

Print stdout and redirect to a file: Tee

Command | Tee file1

Cat A * | Tee-a OUT.txt | Cat-n

-A overwrites the file,-n adds a numeric number to the file

Redirect text blocks inside the script

#！ /bin/bash

Cat<<eof>log.txt

LOG FILE HEADER

This is a test log file

Function:system Staticstics

Eof

Shell Script Usage Tips 2