Add one text to multiple files using bash

Question

I have many files with the extension .com, so the files are named 001.com, 002.com, 003.com, and so on.

And I have another file called headname which contains the following information:

abc=chd
dha=djj
cjas=FILENAME.chk
dhdh=hsd

I need to put the information of the file headname inside (and at the begin of) the files 001.com, 002.com, 003.com and so on... But FILENAME needs to be the filename of the file that will receive the headname information (without the .com extension).

So the output need to be:

For the 001.com:

abc=chd
dha=djj
cjas=001.chk
dhdh=hsd

For the 002.com:

abc=chd
dha=djj
cjas=002.chk
dhdh=hsd

For the 003.com:

abc=chd
dha=djj
cjas=003.chk
dhdh=hsd

And so on...

Something like for f in <files> ; do sed "s/FILENAME/$f/g' headname > "${f}.com" ; done? — Biffen
– Biffen, Commented Jan 21, 2016 at 15:21

Andrea Corbellini · Accepted Answer · 2016-01-21 15:30:45Z

4

set -e

for f in *.com
do
    cat <(sed "s#^cjas=FILENAME.chk\$#cjas=${f%.com}.chk#" headname) "$f" > "$f.new"
    mv -f "$f.new" "$f"
done

Explanation:

for f in *.com -- this loops over all file names ending with .com.
sed is a program that can be used to replace text.
s#...#...# is the substitute command.
${f%.com} is the file name without the .com suffix.
cat <(...) "$f" -- this merges the new head with the body of the .com file.
The output of cat is stored into a file named 123.com.new -- mv -f "$f.new" "$f" is used to rename 123.com.new to 123.com.

edited Jan 21, 2016 at 15:30

answered Jan 21, 2016 at 15:22

Andrea Corbellini

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1 Comment

chepner Over a year ago

Process substitution is an unnecessary complication here; sed ... | cat - "$f" > "$f.new"

Mark Reed · Accepted Answer · 2016-01-21 15:30:03Z

1

Something like this should work:

head=$(<headname)        # read head file into variable
head=${head//$'\n'/\\n}  # replace literal newlines with "\n" for sed
for f in *.com; do       # loop over all *.com files
  # make a backup copy of the file (named 001.com.bak etc).
  # insert the contents of $head with FILENAME replaced by the 
  # part of the filename before ".com" at the beginning of the file      
  sed -i.bak "1i${head/FILENAME/${f%.com}}" "$f"
done

answered Jan 21, 2016 at 15:30

Mark Reed

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