setconf

If there's a textfile with fields like these:

CC=abc
lights := on
compile_today: true

setconf can change the values to something else. It will take the first key it finds and change the value.

setconf can also change values that span over multiple lines, by adding an end string as the last parameter. A typical end string would be ')' or ']'.

You are writing a PKGBUILD for Arch and wish to change a setting without using sed.

Let's say you want to change CC from abc to gcc and that "CC=gcc make" doesn't cut it, for some reason.

Then you can use the following command:

setconf Makefile CC gcc

It aims to solve a tiny problem properly instead of a thousand problems halfway, in true UNIX-spirit.
It can be used with a command that is very easy to read, as opposed to using sed for the same task.
There is less redundancy:

The key does not have to be specified twice.
The old value does not have to be specified.

It should be clear from the syntax what is being done.
It's only one small executable, not a big package.
It can add options and files if they are missing, by using --add.

Setting a value:

sed -i filename 's/key=oldvalue/key=value/g'

setconf filename key value

Setting a value, adding the key and value if missing and creating the file if missing:

grep -q 'x=' file 2>/dev/null && sed 's/x=.*/x=7/g' -i file || echo 'x=7' >> file

setconf -a file x=7

The old value may have to be provided when performing replacements with sed.

Also note that the example using sed will not handle variations in whitespace or in choice of assignment symbol.
setconf supports ==, =>, =, :=, :: and :.

setconf ordinarily takes a filename, key and a new value for that key.
One can also give an optional end string, for replacing multiline values.
It's also possible to add lines with -a or --add.

See the man page or --help output for more information.

The source and issue tracker is available at github.

git clone https://github.com/xyproto/setconf

Arch Linux

pacman -S setconf

See also: package webpage

NetBSD

pkgin install py27-setconf

Or from sources:

cd /usr/pkgsrc/sysutils/py-setconf && make install

Gentoo

emerge -av setconf

openSUSE

zypper install setconf

Void Linux

xbps-install setconf

Manually

It's recommended to install setconf with your distros package management system.

Here is a quick, manual way of installing the latest version of setconf:

curl -s https://setconf.roboticoverlords.org/setconf-0.7.7.tar.xz | tar JxC /tmp
sudo install -Dm755 /tmp/setconf-0.7.7/setconf.py /usr/bin/setconf
sudo install -Dm644 /tmp/setconf-0.7.7/setconf.1.gz /usr/share/man/man1/setconf.1.gz

Run the two last commands as root instead of with sudo, if you prefer.