Replace only on the first matching line with sed

bsdosxregular expressionsedtext processing

Using BSD sed (no GNU extensions), how can I perform an operation similar to the example provided below, but where instead of the line number, the replacement is performed on the first line in which a pattern occurs (rather than having to specify an actual number)?

Restricting to a line number

The simplest restriction is a line number.
If you wanted to delete the first number on line 3, just add a "3" before the command:

sed '3 s/[0-9][0-9]*//' <filename >newfilename

Source: http://www.grymoire.com/Unix/Sed.html#uh-26

Best Answer

{ sed -Ee'/[0-9]+/{s///;q;}'; cat; } <in >out

^should work w/ a BSD sed. but apparently it doesn't.

and so:

sed -e'/[0-9][0-9]*/{s///;:b' -e'n;bb' -e\} <in >out

...should work with any of them.

Related Solutions

sed – Extra Backslash Required in First Appended Newline

It's not exactly documented behaviour, but then the entire thing is an extension. All three commands that were extended similarly (a, i and c) behave the same way: leading whitespace is ignored, and if the text begins with \, then it is discarded. Essentially, it doesn't matter to sed which of these forms are used:

i foo
i \foo
i \
foo

They're all identical. (I know I used i here, but check the the descriptions of a, i and c - it's surreal.)

And the code shows as much:

1111         case 'a':
1112         case 'i':
1113         case 'c':
1114           ch = in_nonblank ();
1115 
1116         read_text_to_slash:
1117           if (ch == EOF)
1118             bad_prog (_(EXPECTED_SLASH));
1119 
1120           if (ch == '\\')
1121             ch = inchar ();

Stuck With Using find and sed to Replace String in Filenames

You can use find -exec ... to do the replacement in a one-line shell script.

find . -name "*.mp3" -type f -exec bash -c 'mv "$1" "${1/pronunciation_de_}"' bash {} \;

The filename {} is passed as parameter $1 to the executed bash process and ${1/pronunciation_de_} makes use of bash's parameter expansion capabilities and replaces the first occurrence of pronunciation_de_ in $1 with an empty string.

Additional option -type f makes sure to match only regular files.

Restricting to a line number

Best Answer

Related Solutions

sed – Extra Backslash Required in First Appended Newline

Stuck With Using find and sed to Replace String in Filenames

Related Question