How to concatenate text from file of lines in format:
line1
line2
...
to get results like
-o line1:1 -o line2:1 ...
I found solution how to concatenate with a separator like this:
ds=`cat list.txt`
${ds//$'\n'/','}
But I can't figure out how to add prefix to each entry.
This depends on what you want to do with the string that you create. It looks like a set of command line options, so I'm going to assume that you want to use it as such together with some utility called util.
Here's a solution for /bin/sh:
#!/bin/sh
listfile=$1
set --
while IFS= read -r line; do
set -- "$@" -o "$line:1"
done <$listfile
util "$@"
This reads from the file given on the command line of the script and for each line read from that file, it sets the positional parameters to include -o and LINE:1 where LINE is the line read from the file.
After reading all the lines, it calls util with the constructed list of command line arguments. By using "$@" (with the double quotes) we ensure that each individual item in the constructed list of arguments is individually quoted.
With bash and using a bash array to hold the command line arguments that we create:
#!/bin/bash
listfile=$1
while IFS= read -r line; do
args+=( -o "$line:1" )
done <$listfile
util "${args[@]}"
In both the examples above, the quoting is important. Likewise is the fact that we create an array of separate items (each -o and each LINE:1 are items in the list). Another way to do it would have been to create a single string -o LINE1:1 -o LINE2:1 etc., but this would have been interpreted as one single argument if used as util "$string" and would have undergone word splitting and filename globbing if used as util $string (this would have not worked if any line in the input file contained spaces, tabs or filename globbing characters).
Both scripts above would be used as
$ ./script.sh file
where script.sh is the executable script file and file is the input file name to read from.
Related:
With a recent shell (e.g. bash), try
mapfile -t TMP <file
TMP=(${TMP[@]/%/:1})
echo ${TMP[@]/#/-o }
-o line1:1 -o line2:1 -o line3:1
sed 's/\(.*\)/-o \1:1/' file.txt | xargs /path/to/command
The sed substitution reads as: replace the text in a given line with "-o the_original_text:1". Then the xargs command takes those modified lines of text and concatenates them as appropriate for command line arguments
Input file:
line1
line2
line3
Command:
perl -lpe '$\=" ";$_="-o $_:1"' input.txt
Alternative command:
awk '{ORS=":1 ";print"-o "$0}' input.txt
Output (the same for both commands):
-o line1:1 -o line2:1 -o line3:1
