bash using a file name as input

Question

Im pretty stupid when in comes to bash and I was hoping someone could help me.

I would like to take the output of

hg resolve -l

which is in the format

R somefile/filename
U somefile/filename
R somefile/filename
U somefile/filename

and be able to use the first line that starts with a 'U' as an argument, so i could do things like

open -t <first U file>

and

hg resolve -m <first U file>

it would be great it someone could give me some pointers about the best way to do this!

Thanks

EDIT: solution from answers below, a simple script. Thanks guys!

#!/bin/bash

# Script that gets the first file from hg resolve | grep U and passes to default text editor

first_u_file=$(hg resolve -l | grep -m1 '^U')
first_u_file=${first_u_file#U }
echo opening \'$first_u_file\'
open -t "$first_u_file"

echo "opening '$first_u_file'" - you don't need to escape the single quotes and the variable gets properly quoted. — Dennis Williamson, May 31 '12 at 11:16

Stephane Chazelas · Accepted Answer · 2012-10-02 19:47:10Z

up vote 3 down vote accepted

With GNU grep, you can try this (untested):

first_u_file=$(hg resolve -l | grep -m1 '^U')
first_u_file=${first_u_file#U }

-mX tells grep to stop after printing X lines, 1 in this case. The $(...) construct is similar to backticks, it turns output into a string. The second line removes "U " from the beginning of the file name.

edited Oct 2 '12 at 19:47

Stephane Chazelas
48.6k542112

answered May 31 '12 at 9:07

choroba
3,322312

where does this need to live? is this an alias? sorry for my minimal understanding!! – Dori May 31 '12 at 9:14

@Dori You can now use the variable, as in open -t "$first_u_file" and so on. – choroba May 31 '12 at 9:31

+1 great thanks! it works!! So whats going on here? If i enter the above first_u_file lines in bash it works, i tried to put them in bash_profile and it does not work. How can store this permenantly in some config file? – Dori May 31 '12 at 9:45

@Dori What exactly do you need to keep stored? – choroba May 31 '12 at 9:51

1

@Dori: Functions and commands only return their exit status, not string. But you can create a script or a function that prints (echo-es) the value and then run open -t $(grab_first_file_name). – choroba May 31 '12 at 10:26

show 5 more comments

William Pursell · Answer 2 · 2012-05-31 12:23:24Z

up vote 2 down vote

A simpler solution:

u_file=$( hg resolve -l | awk '/^U/{print $2; exit}' )

answered May 31 '12 at 12:23

William Pursell
58937

LeleDumbo · Answer 3 · 2012-05-31 09:02:55Z

up vote 1 down vote

hg resolve -l | egrep '^U.*' | head -n 1

the output is the first U file

to use it as open argument with "U" dropped:

firstUfile=`hg resolve -l | egrep '^U.*' | head -n 1 | sed -e 's/^U\s+\(.*\)$/"\1"/'`
open -t $firstUfile

answered May 31 '12 at 9:02

LeleDumbo

+1 thanks, a good start. So how do I use this as an input for open -t. I need to remove the 'U ' also I presume – Dori May 31 '12 at 9:11

I've edited to include U removal, I've put double quotes around the filename in case it has spaces, if you don't need it, feel free to remove from the sed substitution – LeleDumbo May 31 '12 at 9:21

this does not seem to remove the 'U ' ? Do i jut put this in .bash_proile with a preceeding alias ? – Dori May 31 '12 at 9:30

ah i see, its a variable, ok! executing that string of piped commands still gives me the preceeding U :( – Dori May 31 '12 at 9:40

chepner · Answer 4 · 2012-05-31 14:20:01Z

Rather than just open the first file, your script could iterate over all unresolved files:

#!/bin/bash

while read; do
    file="${REPLY#U }"
    echo "Opening '$file'"
    open -t "$file"      
    hg resolve -m "$file"
done <( hg resolve -l | grep "^U" )

(I'm not familiar with hg; would hg resolve -aln give you just the list of unresolved files without the "U" prefix? That would do away with the need for the grep and the U-stripping step.)

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bash using a file name as input

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