CODEWITHSUNDEEP
bash
cade galt
cade galt

Reputation: 4171

How can I serialize bash commands?

I just want to do a simple greeting:

I tried:

echo "Welcome " + whoami

echo "Welcome " . whoami

and finally

echo "Welcome "; whoami

came close but it added a return character between the statements like this

Welcome 
user

I want the output to be:

Welcome user

In general I want this to work:

#run
run(){
    rc
    show
    pwd
    a=whomai
    b=pwd
    c=timestamp
    echo "Welcome $a, you are in $b, and the time is $c"
}

run

Upvotes: 0

Views: 886

Answers (2)

Charles Duffy
Charles Duffy

Reputation: 295629

echo emits a newline at the end of its output, and the usual ways to avoid this (with -n) are not required to be supported by the POSIX standard (POSIX leaves echo behavior undefined with a wide array of inputs, making it undesirable for use with non-constant strings). Use printf instead:

printf 'Welcome '; whoami

That said, if you want to assign output of a command to a variable, use command substitution:

a=$(whoami)
printf '%s\n' "Welcome, $a"

This can also be inlined:

printf '%s\n' "Welcome, $(whoami)"

Thus:

run() {
    local a b c          # declare locals to avoid polluting namespace outside function

    a=${USER:-$(whoami)} # only call $(whoami) if $USER is unset
    b=$PWD               # more efficient than $(pwd), which runs a subshell
    c=$(date)            # for bash 4, this could be instead: printf -v c '%(%T)T' 0
                         # ...which would avoid calling external commands, and thus also
                         # ...be more efficient.
    printf '%s\n' "Welcome $a, you are in $b, and the time is $c"
}

Upvotes: 2

Hellmar Becker
Hellmar Becker

Reputation: 2982

echo "Welcome $(whoami)"

should do the trick.

Upvotes: 2

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