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In a shell script, how do I echo all shell commands called and expand any variable names?
For example, given the following line:
ls $DIRNAME I would like the script to run the command and display the following
ls /full/path/to/some/dir The purpose is to save a log of all shell commands called and their arguments. Is there perhaps a better way of generating such a log?
613
Explanation: echo will print the command but not execute it. Just omit it to actually execute the command.
The shell parses the command line and finds the program to execute. It passes any options and arguments to the program as part of a new process for the command such as ps above. While the process is running ps above the shell waits for the process to complete.
Examples of Echo Command For instance, using \c let you shorten the output by omitting the part of the string that follows the escape character: echo -e 'Hello, World! \c This is PNAP! '
set -x or set -o xtrace expands variables and prints a little + sign before the line.
set -v or set -o verbose does not expand the variables before printing.
Use set +x and set +v to turn off the above settings.
On the first line of the script, one can put #!/bin/sh -x (or -v) to have the same effect as set -x (or -v) later in the script.
The above also works with /bin/sh.
See the bash-hackers' wiki on set attributes, and on debugging.
$ cat shl #!/bin/bash DIR=/tmp/so ls $DIR $ bash -x shl + DIR=/tmp/so + ls /tmp/so $ If you love us? You can donate to us via Paypal or buy me a coffee so we can maintain and grow! Thank you!
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