how do I add static text in addition to ls results when using tee command

[cris7]

I'm running the following:

ls *.dbf | tee filename

This creates a file called filename, and puts the results of ls *.dbf into that file, with a separate line for each file ls returns:

example1.dbf
test1.dbf
here_it_is.dbf

I then go in and manually add ~~~ at the beginning of each line in filename:

~~~example1.dbf
~~~test1.dbf
~~~here_it_is.dbf


Is there a way to incorporate the ~~~ addition into the command so that every line in filename begins with ~~~?

Please help, and thanks!

[matt_symes]

Hi

You could do something like this.

Move into the directory you want and type.

for f in *.dbf; do printf "~~~%s\n" "$f"; done > filename

This will not recurse into child directories.

Kind regards

[cris7]

Thanks matt_symes!


I also found that this worked...

ls *.dbf | tee runfile | awk '$0="~~~"$0' > filename


Not sure if your example or mine really make a difference, I'm still pretty new at this.

I did turn my example above into an executable script and will now run it whenever I need to generate the file...

Thanks again!

[matt_symes]

Hi

Not sure if your example or mine really make a difference, I'm still pretty new at this.

One difference is that the pipeline is slightly slower as it forks more processes and this is expensive. This can make a real difference on large datasets and depending on how you code your scripts.

For one file

matthew-laptop:/home/matthew:3 % ls *.dbf
test.dbf
matthew-laptop:/home/matthew:3

matthew-laptop:/home/matthew:3 % time ( for f in *.dbf; do printf "~~~%s\n" "$f"; done > filename )
( for f in *.dbf; do; printf "~~~%s\n" "$f"; done > filename; )  0.00s user 0.00s system 77% cpu 0.002 total
matthew-laptop:/home/matthew:3 %

time (ls *.dbf | tee runfile | awk '$0="~~~"$0' > filename)
( ls -F --color=auto *.dbf | tee runfile | awk '$0="~~~"$0' > filename; )  0.00s user 0.01s system 94% cpu 0.007 total
matthew-laptop:/home/matthew:3 %

However in this case the difference is so small (at least for one file), we'll ignore it

Obviously one would want an averaged time to get more accurate results.

Kind regards