How to make bash scripts print out every command before it executes?

How to make bash scripts print out every command before it executes?
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4


For example, I have a simple bash file

#!/bin/bash
cd ~/hello
ls

How can I make it display every command before executing it? Just the opposite effect of "@echo off" in windows batch scripting.
bash scripting
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asked May 31 '09 at 13:39
Epeius
7326

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7 Answers
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up vote 28 down vote accepted


bash -x script

or

set -x

in the script
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answered May 31 '09 at 13:44
Steven Parkes
39534


I have always used this to great effect. The output looks a little dirtier than you might first expect. – Scott Pack May 31 '09 at 13:51
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up vote 10 down vote


These also work:

set -v

or

#!/bin/bash -v

But -v doesn't print the PS4 string before each script line and it doesn't trace the steps of a "for" statement (for example) individually. It does echo comments while -x doesn't.

Here's an example of the output using -v:

#!/bin/bash -v
# this is a comment
for i in {1..4}
do
echo -n $i
done
1234echo

echo hello
hello

Here's the result of the same script with -x:

+ for i in '{1..4}'
+ echo -n 1
1+ for i in '{1..4}'
+ echo -n 2
2+ for i in '{1..4}'
+ echo -n 3
3+ for i in '{1..4}'
+ echo -n 4
4+ echo

+ echo hello
hello

Note that I included "echo -n" to add emphasis to the differences between -v and -x. Also, -v is the same as "-o verbose", but the latter seems not to work as part of a shebang.