Bash how to feed multiple command line arguments to Xgraph

Question

Using the Xgraph data plotting tool (XGRAPH), I want to plot a bunch of files named test1.csv test2.csv, ...

The command would be

xgraph -columns 1 2 test1.csv -columns 1 2 test2.csv

and so on· Is there any way I can use brace expansion or some other magic to circumvent manually typing the pattern -columns 1 2 file.csv again and again?

`my_function(){ for f ; do xgraph -columns 1 2 "$f"; done; }; my_function test{1..100}.csv` — Jetchisel, Jun 19 '23 at 22:23

J.Peace · Accepted Answer · 2023-06-20T17:06:01.220

3

I think this function should work for you...

graph-build() {
  # loop through commandline filenames and join together
  for file in "${@}"; do
    cmd_build+=(-columns 1 2 "${file}")
  done
  # run xgraph
  xgraph "${cmd_build[@]}"
}

# Run with the expansion as required.
graph-build file{1..3}.csv

Edit: Syntax updated due to helpful comments highlighting the whitespace issue with filenames in my initial revisions.

edited Jun 20 '23 at 17:06

answered Jun 19 '23 at 22:05

J.Peace

71
4

3

use bash arrays to build arguments – KamilCuk Jun 19 '23 at 22:25
1

You could use an array, but I have to ask, what is wrong with the method I chose? – J.Peace Jun 19 '23 at 22:50
3

https://mywiki.wooledge.org/BashFAQ/050 That for exmaple files with spaces will not work. Check your scripts with shellcheck – KamilCuk Jun 19 '23 at 22:55
1

Thanks, I will amend. I found another source explaining as well. I still have to shake off old habits :) – J.Peace Jun 19 '23 at 23:00
1

Thank you, it works well! Just one typo "-column" should be "-columns" for future reference. – reloh100 Jun 20 '23 at 15:21
Ahh.. Thanks for letting me know. Corrected :) – J.Peace Jun 20 '23 at 17:06

score 1 · Answer 2 · answered Jun 19 '23 at 23:08

With the specific set of filenames given in the question you can use brace expansion and eval to replace

xgraph -columns 1 2 test1.csv -columns 1 2 test2.csv ... -columns 1 2 test10.csv

with

eval xgraph ' -columns 1 2 test'{1..10}'.csv'

eval is dangerous in general, and is best avoided. See Why should eval be avoided in Bash, and what should I use instead?. It's safe in this case, because there are no variable expansions involved in the expression.

Bash how to feed multiple command line arguments to Xgraph

2 Answers2