Bash – convenient way to wrap a bash command list into rlwrap

bashcommand lineline-editor

Thanks to a question on superuser.com, I found out about this utterly convenient rlwrap tool.

It satisfies my needs (i.e. add command history to another cmdline tool), but I was wondering how I can use it to add command history to a 'compound' shell command, like the prototypical

$> while read line; do echo "i read $line"; done
hi
i read hi
^D

When I put the while loop inside a shell script, and execute it like rlwrap ./whilereadline.sh, it's ok.

But I'm wondering how I can do this without the need for an additional file, somewhat like

$> rlwrap (while read line; do echo "line: $line"; done)
bash: syntax error near unexpected token `while'

Any ideas?

Best Answer

Have you tried

rlwrap sh -c 'while read line; do echo "i read $line"; done'

rlwrap needs a command it can run, which a () syntax-induced subshell is not. sh -c ... is a command however. Replace sh with bash or whatever shell you prefer.

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Shell – Running a program with several parameters using shell script

You can use a for loop:

for iteration in 10 100 1000 10000 100000; do
    python -W ignore Experiment.py --iteration "${iteration}"
done

If you have multiple parameters, and you want all the various permutations of all parameters, as @Fox noted in a comment below, you can use nested loops. Suppose, for example, you had a --name parameter whose values could be n1, n2, and n3, then you could do:

for iteration in 10 100 1000 10000 100000; do
    for name in n1 n2 n3; do
         python -W -ignore Experiment.py --iteration "${iteration}" --name "${name}"
    done
done

You could put that in a file, for example runExperiment.sh and include this as the first line: #!/bin/bash. You could then run the script using either:

bash runExperimen.sh

Or, you could make the script executable, then run it:

chmod +x runExperiment.sh
./runExperiment.sh

If you're interested in some results before others, that'll guide how you structure the loops. In my example above, the script will run:

... --iteration 10 --name n1
... --iteration 10 --name n2
... --iteration 10 --name n3
... --iteration 100 --name n1

So it runs all experiments for iteration 10 before moving on to the next iteration. If instead you wanted all experiments for name n1 before moving on to the next, you could make the name loop the "outer" loop.

for name in ...; do
    for iteration in ...; do

Best Answer

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