Saturday, 20 July 2013

vimdiff tips and tricks - how to copy between two screens

do (diff obtain) and dp (diff put) is what you need. Here is a small list of other helpful commands in this context.
]c               - advance to the next block with differences
[c               - reverse search for the previous block with differences
do (diff obtain) - bring changes from the other file to the current file
dp (diff put)    - send changes from the current file to the other file
zo               - unfold/unhide text
zc               - refold/rehide text
zr               - unfold both files completely
Note: Both do and dp work if you are on a block or just one line under a block.
:diffupdate will re-scan the files for changes

Wednesday, 3 July 2013

Debugging / Tracing bash shell scripts

Watching your script run

It is possible to have bash show you what it is doing when you run your script. To do this, add a "-x" to the first line of your script, like this:
#!/bin/bash -x
Now, when you run your script, bash will display each line (with substitutions performed) as it executes it. This technique is called tracing. Here is what it looks like:
[me@linuxbox me]$ ./trouble.bash
+ number=1
+ '[' 1 = 1 ']'
+ echo 'Number equals 1'
Number equals 1
Alternately, you can use the set command within your script to turn tracing on and off. Use set -x to turn tracing on and set +x to turn tracing off. For example.:


set -x
if [ $number = "1" ]; then
    echo "Number equals 1"
    echo "Number does not equal 1"
set +x