Linux EXEC Usage Summary

Summary of exec usage in Linux

Summarize a table first:

exec command	action
exec ls	ls Span style= "font-family: the song Body;" >, No return to the original after the end
exec  <file	exec standard input
exec  >file
exec  3<file	read into fd3 Span style= "font-family: the song Body;" > in
sort  <&3	fd3
exec  4>file	will be written to file Span style= "font-family: the song Body;" > in
ls  >&4	ls fd4
exec  5<&4	create fd5
EXEC 3<&-	Close fd3

1. exec Execution program

Althoughexecand theSourceis executed directly in the parent process, butexecthis andSourceThere's a big difference,Sourceis to performShellscript, and will return to the previousShell. andexecexecution does not return to the previousShell, but directly to the previous landingShellas a procedure, it is copied on the line.

2. exec Example

1) Exec </dev/tty1//function: Use the serial terminal display character as input to exec

For example, in the key input driver: After executing exec </dev/tty1, press the key on the Development Board, the serial terminal displays the characters pressed,

Then press the OK key on the Development Board, the command will be executed, and the confirmation key will be invalid on the computer serial terminal.