shell block redirect

Code block as a whole by a plurality of statements, for, while, until the cycle or if ... else, case ... in selecting structures, or by the {} of a command are called code blocks.

At the end of the block on the redirect command, redirection can be implemented for all the commands in the code block.

For Li

While loop continues to read the digital nums.txt, their sum is calculated. #!/bin/bash sum=0 while read n; do ((I  + n )) DONE  <the nums .txt  # input redirection echo "sum=$sum"	Test.sh to save the code and run: cat nums.txt 80 33 129 71 100 222 8 . ./test.sh sum=643
Reading process while recording, and to redirect the output log.txt file: #!/bin/bash sum=0 while read n; do ((I  + n )) echo "this number: $n" DONE  <the nums .txt  > log .txt  # simultaneously input and output redirection echo "sum=$sum"	. ./test.sh sum=643 cat log.txt this number: 80 this number: 33 this number: 129 this number: 71 this number: 100 this number: 222 this number: 8
Of {}the code enclosed redirection. #!/bin/bash { echo "aa"; echo "bb"; echo "cc" }  > Log .txt  # output redirection { read name; read url; read age }  <Log .txt  # input redirection echo  "$ name has $ age years old, it is the URL $ url"	. ./Test.sh aa bb-year-old already, and it is the URL cc cat log.txt aa bb cc