Write Output of Bash Command to Log File
To write output of Bash Command to Log File, you may use right angle bracket symbol (>) or double right angle symbol (>>).
Right angle braketsymbol (>) : is used to write output of a bash command to a disk file. If the file is not already present, it creates one with the name specified. If the file is already present, the content of the file would be overwritten.
Double right angle symbol (>>) : is used to append data to an existing file. If the file is not already present, a new one would be created.
When you are writing to the file for the first time, and want no previous data to be in the file if it is already present, use (>) to make sure that it overwrites the content. And in the later script, you may use (>>) to append to the log file.
Following is an example to demonstrate writing output of Bash Commands to Log File.
Bash Script File
#!/bin/bash log=log_file.txt # create log file or overrite if already present printf "Log File - " > $log # append date to log file date >> $log x=$(( 3 + 1 )) # append some data to log file echo value of x is $x >> $log
When you run the above bash script, following file would be created with the content specified.
Log File - Fri Dec 15 11:47:03 IST 2017 value of x is 4
In this Bash Tutorial, we learned how to write the output of a Bash command to a file.