6

I have tried doing:

echo " mv /server/today/logfile1 /nfs/logs/ && gzip /nfs/logs/logfile1" | sed 's|logfile1|logfile2|g'

It printed:

mv /server/today/logfile2 /nfs/logs/ && gzip /nfs/logs/logfile2

which is a bash command. How can I make it get executed, instead of just printing it?

dhag
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Raja G
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    I tried to answer your question as formulated, but it's not obvious to me how this is useful; are you actually trying to accomplish something more complicated? – dhag Nov 20 '15 at 14:42
  • @dhag and upvoter Yes it will help me to move log files with out using side keys. – Raja G Nov 20 '15 at 14:47
  • @dhag my initial question is http://unix.stackexchange.com/questions/243317/bash-how-can-i-replace-a-string-in-a-previous-command but at comment given for answer I have mentioned my problem. I am trying to solve it but stuck here.... If you still want more information why I need to get this. – Raja G Nov 20 '15 at 14:51
  • Is your actual problem that you have a bunch of files within /server/today/, and that you would like to move and gzip all of them? If so, I will suggest a simpler / safer solution. – dhag Nov 20 '15 at 14:55
  • @dhag please go on – Raja G Nov 20 '15 at 16:42
  • You'll get better answers when you tell why you're trying to do something, and you're desired end result. There are many valid answers to your question that won't help you achieve you goal. Explaining the context of the problem helps get better answers. – RobertL Nov 20 '15 at 19:18

3 Answers3

10

You could pipe your command into a shell so it gets executed:

echo "mv ..." | bash

Or you could pass it as an argument to a shell:

bash -c "$(echo "mv ...")"

Or you could use the bash built-in eval:

eval "$(echo "mv ...")"

Note, however, that all of those code-generating commands look a bit brittle to me (there are ways they will fail as soon as some of the paths contain spaces, etc.).

dhag
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2

You're reimplementing history substitution.

$ mv /server/today/logfile1 /nfs/logs/ && gzip /nfs/logs/logfile1
$ !!:gs/logfile1/logfile2

If you haven't actually executed the first command yet, and just want to execute a set of similar commands, consider a loop:

for f in logfile logfile2; do
    mv /server/today/"$f" /nfs/logs && gzip /nfs/logs/"$f"
done
chepner
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  • I have similar script that does same as your 2nd script do but the 1st one is impressive . Thank you. – Raja G Nov 21 '15 at 10:14
0

It can also be done with xargs:

echo "mv ..." | sed "..." | xargs command

Examples:

$ echo "whoareyou" | sed "s/areyou/ami/g" | xargs command

username
  • If there are && or similar, you also need eval:
$ echo "whoareyou && whoareyou" | sed "s/areyou/ami/g" | xargs command eval

username
username

To also print what command is executed:

  • xargs -t
$ echo "whoareyou && whoareyou" | sed "s/areyou/ami/g" | xargs -t command eval

command eval whoami '&&' whoami
username
username
  • tee
echo "whoareyou && whoareyou" | sed "s/areyou/ami/g" | tee >(sh)

whoami && whoami
username
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manero
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