Bash comments can only be done as single-line comment using the hash character # . Every line or word starting by the # sign cause all the following content to be ignored by the bash shell. This is the only way to do a bash comment and ensure text or code is absolutely not evaluated in Bash.
A single-line comment starts with hashtag symbol with no white spaces (#) and lasts till the end of the line. If the comment exceeds one line then put a hashtag on the next line and continue the comment. The shell script is commented out prefixing # character for single-line comment.
Inline comments are comments made by an instructor that appear directly on top of your paper. These comments are usually brief.
My preferred is:
Commenting in a Bash script
This will have some overhead, but technically it does answer your question
echo abc `#put your comment here` \ def `#another chance for a comment` \ xyz etc
And for pipelines specifically, there is a cleaner solution with no overhead
echo abc | # normal comment OK here tr a-z A-Z | # another normal comment OK here sort | # the pipelines are automatically continued uniq # final comment
How to put a line comment for a multi-line command
I find it easiest (and most readable) to just copy the line and comment out the original version:
#Old version of ls:
#ls -l $([ ] && -F is turned off) -a /etc
ls -l -a /etc
$(: ...)
is a little less ugly, but still not good.
Here's my solution for inline comments in between multiple piped commands.
Example uncommented code:
#!/bin/sh
cat input.txt \
| grep something \
| sort -r
Solution for a pipe comment (using a helper function):
#!/bin/sh
pipe_comment() {
cat -
}
cat input.txt \
| pipe_comment "filter down to lines that contain the word: something" \
| grep something \
| pipe_comment "reverse sort what is left" \
| sort -r
Or if you prefer, here's the same solution without the helper function, but it's a little messier:
#!/bin/sh
cat input.txt \
| cat - `: filter down to lines that contain the word: something` \
| grep something \
| cat - `: reverse sort what is left` \
| sort -r
If you love us? You can donate to us via Paypal or buy me a coffee so we can maintain and grow! Thank you!
Donate Us With