如何在Unix/Linux下调试脚本程序

command

Bash shell offers debugging options which can be turn on or off using set command.
=> set -x : Display commands and their arguments as they are executed.
=> set -v : Display shell input lines as they are read.

You can use above two command in shell script itself:

#!/bin/bash clear # turn on debug mode set -x for f in * do file $f done # turn OFF debug mode set +x ls # more commands 

You can replace standard
#!/bin/bash
with (for debugging)
#!/bin/bash -xv

Method # 3: Use of intelligent DEBUG function

Add special variable _DEBUG. Set to `on’ when you need to debug a script:
_DEBUG="on"

Put the following function at the beginning of the script:

function DEBUG() { [ "$_DEBUG" == "on" ] && $@ || : }

Now wherever you need debugging simply use DEBUG function
DEBUG echo "File is $filename"
OR
DEBUG set -x
Cmd1
Cmd2
DEBUG set +x

When debugging done and before moving a script to production set _DEBUG to off
No need to delete debug lines.
_DEBUG="off" # set to anything but not to 'on'

Sample script:

#!/bin/bash _DEBUG="on" function DEBUG() { [ "$_DEBUG" == "on" ] && $@ || : } DEBUG echo 'Reading files' for i in * do grep 'something' $i > /dev/null [ $? -eq 0 ] && echo "Found in $i file" || : done DEBUG set -x a=2 b=3 c=$(( $a + $b )) DEBUG set +x echo "$a + $b = $c" 

Save and run the script:
$ ./script.sh
Output:

Reading files Found in xyz.txt file + a=2 + b=3 + c=5 + DEBUG set +x + '[' on == on ']' + set +x 2 + 3 = 5 

Now set DEBUG to off
_DEBUG="off"
Run script:
$ ./script.sh
Output:

Found in xyz.txt file 2 + 3 = 5 

Above is a simple but quite effective technique. You can also try to use DEBUG as an alias instead of function.