CODEWITHSUNDEEP
bashshellunixawkalias
dmc
dmc

Reputation: 411

Using pipes in an alias

I have this in my .bashrc:

alias jpsdir="jps | awk '{print $1}' | xargs pwdx"

but when I use jpsdir I get this output:

pwdx: invalid process id: JvmName

but running

jps | awk '{print $1}' | xargs pwdx

gives the correct results:

1234: /some/dir/

What is wrong with my alias? Should i make it a function ?

Upvotes: 6

Views: 7419

Answers (2)

Vahn Lewis
Vahn Lewis

Reputation: 1

Been trying to run : date | awk '{print $5}' as a command to extract the time from the date command. When I run "time" as a command, I get this gibberish:

time

real    0m0.000s
user    0m0.000s
sys     0m0.000s

So the time is the 5th string item in the date command and I was so pleased when I plucked it out using an awk command, my first attempt at using awk. As Tom French's answer suggests if you get rid of the $x above, the command prints the entire date string. It didn't take me very many attempts using the alias command before I came upon a pretty simple example that wouldn't run.

Upvotes: 0

Tom Fenech
Tom Fenech

Reputation: 74635

As gniourf_gniourf has explained in the comments, the reason that your alias wasn't working was because the $1 in your awk command was being expanded by the shell. The value is likely to be empty, so the awk command becomes {print } and pwdx is being passed both parts of the output of jps.

You can avoid having to escape the $ by avoiding using awk entirely; you can use the -q switch rather than piping to awk:

jpsdir() {
    jps -q | xargs pwdx
}

I would personally prefer to use a function but you can use an alias if you like.

Upvotes: 10

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