Manage directory navigation with pushd and popd

UNIX supports a wide variety of directory-navigation tools. Two good tools are pushd and popd.

You're certainly aware that the cd command changes your current directory. What happens if you have several directories to navigate, but you want to be able to quickly return to a location? The pushd and popd commands create a virtual directory stack, with the pushd command changing your current directory and storing it on the stack, and the popd command removing the directory from the top of the stack and returning you to that location. You can use the dirs command to display the current directory stack without pushing or popping a new directory. Listing below shows how you can use the pushd and popd commands to quickly navigate the directory tree.

$ pushd .
~ ~
$ pushd /etc
/etc ~ ~
$ pushd /var
/var /etc ~ ~
$ pushd /usr/local/bin
/usr/local/bin /var /etc ~ ~
$ dirs
/usr/local/bin /var /etc ~ ~
$ popd
/var /etc ~ ~
$ popd
/etc ~ ~
$ popd
~ ~
$ popd

The pushd and popd commands also support parameters to manipulate the directory stack. Using the +n or -n parameter, where n is a number, you can rotate the stack left or right, as shown below

$ dirs
/usr/local/bin /var /etc ~ ~
$ pushd +1
/var /etc ~ ~ /usr/local/bin
$ pushd -1
~ /usr/local/bin /var /etc ~

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Reuse previous arguments

Here is another great tip from IBM. I love this. The !$ command returns the last argument used with a command. But what happens if you have a command that used arguments and you want to reuse just one of them?

The !:1 operator returns the argument used in a command. The example in Listing 3 shows how you can use this operator in combination with the !$ operator. In the first command, a file is renamed to a more meaningful name, but to preserve use of the original file name, a symbolic link is created. The file kxp12.c is renamed in a more readable manner, then the link command is used to create a symbolic link back to the original file name, in case it's still used elsewhere. The !$ operator returns the file_system_access.c argument, and the !:1 operator returns the kxp12.c argument, which is the first argument of the previous command.

$ mv kxp12.c file_system_access.c
$ ln –s !$ !:1

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Use history expansion

This post is from Unix tips from IBM. What happens if you're using the same file name for a series of commands? Well, there's a shortcut that can quickly retrieve the last file name you used.

What happens if you're using the same file name for a series of commands? Well, there's a shortcut that can quickly retrieve the last file name you used. As shown below, the !$ command returns the file name that the previous command used. The file this-is-a-long-lunch-menu-file.txt is searched for occurrences of the word pickles. After searching, the vi command is used to edit the this-is-a-long-lunch-menu-file.txt file without the need for retyping the file name. You use the bang, or exclamation point (!), to access the history, and the dollar sign ($) returns the last field of the previous command. It's a great tool if you are using long file names repeatedly.

$ grep pickles this-is-a-long-lunch-menu-file.txt
pastrami on rye with pickles and onions
$ vi !$

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