Parsing text with bash script

Question

I want to build a bash script that reads a file and produces some command line parameters. my input file looks like

20.83      0.05     0.05  __adddf3
20.83      0.10     0.05  __aeabi_fadd
16.67      0.14     0.04  gaussian_smooth
8.33      0.16     0.02   __aeabi_ddiv

I must detect and copy all the __* strings and turncate them into a command such as

gprof -E __adddf3 -E __aeabi_fadd -E __aeabi_ddiv ./nameof.out

So far I use

#!/bin/bash
while read line
do
    if [[ "$line" == *__* ]] 
    then
        echo $line;
    fi
done <input.txt

to detect the requested lines but i guess, what i need is a one-line-command thing that i can't figure out. Any kind suggestions?

@jordanm: I said "fin" probably because I was looking at the name of the person who edited this question. ;-) — Dennis Williamson
– Dennis Williamson, Commented Jun 2, 2012 at 7:35
@shellter: It means equal here, too. It's just equal to something with wildcards. — Dennis Williamson
– Dennis Williamson, Commented Jun 2, 2012 at 14:17

Dennis Williamson · Accepted Answer · 2012-06-02 10:43:50Z

3

Modifying your script:

#!/bin/bash
while read -r _ _ _ arg
do
    if [[ $arg == __* ]] 
    then
        args+=("-E" "$arg")
    fi
done <input.txt
gprof "${args[@]}" ./nameof.out

The underscores are valid variable names and serve to discard the fields you don't need.

The final line executes the command with the arguments.

You can feed the result of another command into the while loop by using process substitution:

#!/bin/bash
while read -r _ _ _ arg
do
    if [[ $arg == __* ]] 
    then
        args+=("-E" "$arg")
    fi
done < <(gprof some arguments filename)
gprof "${args[@]}" ./nameof.out

edited Jun 2, 2012 at 10:43

answered Jun 2, 2012 at 3:46

Dennis Williamson

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Comments

ghoti · Accepted Answer · 2012-06-02 03:51:12Z

3

One more way to skin the cat:

gprof `sed -ne '/__/s/.* / -E /p' input.txt` ./nameof.out

The sed script searches for lines with __, then changes everything up to the last space with -E and prints the result. You may have to adjust things a little if your whitespace could include tabs. For clarity, I didn't account for that here.

answered Jun 2, 2012 at 3:51

ghoti

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Comments

Prince John Wesley · Accepted Answer · 2012-06-02 03:41:02Z

2

Using awk:

awk '$4 ~/^__/{a=a" -E "$4}END{system("gprof "a" ./nameof.out")}' inputFile

edited Jun 2, 2012 at 3:41

answered Jun 2, 2012 at 3:20

Prince John Wesley

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4 Comments

Dimitris Over a year ago

That is perfect! I just need to turn that print into an executable command, so run instead of print.

Dimitris Over a year ago

system() instead of print is the answer! :-)

ghoti Over a year ago

@user1431903 - don't forget to "accept" the answer by clicking on the arrow.

Dimitris Over a year ago

@ghoti I didn't. I'm just searching for a solution without awk

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