If you had used double quotes, here's what your actual sed command would have been like: $ sed "s/`date`/`uptime`/" Here's a good example: $ echo 'SELECT `date` FROM `services`' | sed 's/`date`/`uptime`/' When using double quotes, however, your string is going to be interpreted by the shell before being passed on to sed, and you must take into account any modifications, some of which might not be what you want. It's very simple when the command is enclosed in single quotes: what you see is exactly what sed sees. It seems that double quotes enable some nice functionality, so why not always use them? The main reason for me is not always seeing what command is actually being executed by sed. That second point usually means that your COLUMNS variable will only be set in your interactive shell, not in a bash script. Tip: The working directory for the new terminal depends on the setting. Trigger the (Windows, Linux Ctrl+Shift+5) command. Alt and click on a tab, the + button, or the single tab on the terminal panel. Set automatically upon receipt of a SIGWINCH signal. Right-click the context menu and selecting the Split menu option. ![]() Here's a couple of examples where using double quotes makes perfectly sense: $ echo "We're good!" | sed "s/'re/ are/" It is an ordinary bash parameter that is set by bash itself. ![]() The most common cases that come to mind are single quotes inside text strings and shell variable interpolation. ![]() My advice would be sticking to single quotes, unless you know what you're doing and need to take advantage of some command-line functionality. Further study of central nervous action, however, finds central inhibition too extensive and ubiquitous to make it likely that it is confined solely to the taxis of antagonistic muscles. Bury me by my grand-grand and when you can, come follow me. I'm expanding my earlier comments into an answer. Lil Layzie came to me, told me if he should decease well then please.
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