10 shell secrets that will change your life FOREVER!

by Malcolm Locke on at Christchurch Ruby

Spoiler: There are only 5

cd -

Change into the directory you were in before this one. See also pushd and popd to maintain a directory stack.

CTRL+O

Use this instead of pressing enter to execute the current item in the history and advance to the subsequent item. Very useful for edit / compile / test cycles.

Note: not available by default on Mac

seq

Very useful for generating sequences in the shell.

$ for i in `seq 1 5` ; do echo $i ; done
1
2
3
4
5

${VAR-DEFAULT}

Specify an overridable default for a shell variable, great in scripts.

$ cat default-var.sh
#!/bin/bash
DIR=${SPECIAL_DIR-$HOME}
echo "DIR = $DIR"

$ ./default-var.sh
DIR=/home/malc

$ SPECIAL_DIR=/foo ./default-var.sh
DIR=/foo

ESC .

Insert the last argument of the last command in the history at the cursor. Great performing a set of command on the same file

$ touch /really/long/filename.txt
$ chown malc:malc <ESC> <.>
$ chmod 644 <ESC> <.>
$ vi <ESC> <.>

Available as ALT+. on Linux.

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