Allows you to enter search strings that include the typical set of characters included in various programming languages.→ Continue reading “Internet Search for Code: SymbolHound”
Category: Computers
All things computing.
Print Lines in a File From a Specific Line Number Until the End of the File with sed
If you know that you want all of the lines in a given file from n to EOF the following is the sed command:
sed -n '3,$p' some_file.txtTo print out lines 2 – 5 simply modify it to:
sed -n '2,5p' some_file.txtRemoving the Last Token From a String in Bash with awk
Let’s say that you have some number of files for which you want to create a containing directory that is named with all but the last token of the file name, and you want to remove just the last token to create the name of the directory.
Much easier to explain with an example. Given this list of files:
ls -1
foo_10_10_sometrash
foo_1_sometrash
foo_2_sometrash
foo_3_sometrash
foo_4_sometrash
foo_5_5_sometrash
foo_5_sometrash
foo_6_6_sometrash
foo_7_7_sometrash
foo_8_8_sometrash
foo_9_9_sometrashYou want to create a directory for each → Continue reading “Removing the Last Token From a String in Bash with awk”
Backspace, Delete, and/or Return Key Stops Working in Oracle SQL Developer
So, I fire up SQL Developer to run some queries against a QC server and for some reason, I am no longer able to use the backspace, delete, or return keys to edit .sql files opened in the program.
I tried opening a new .sql file, and restarting SQL Developer. I then tried restarting Windows. None of those worked.
After a bit of searching I found a forum posting that indicated by going to Tools/Preferences/Accelerators and clicking the “Load Preset…” → Continue reading “Backspace, Delete, and/or Return Key Stops Working in Oracle SQL Developer”
Checking that Input or a Variable is an Integer in BASH
Here is a quick snippet for checking whether or not a variable is a valid integer in BASH. It is also a howto for regular expressions in a shell script.
# Make sure that FOO is an integer
if [[ ! "$FOO" =~ ^[0-9]+$ ]]; then
echo "The FOO was NOT an integer"
fiHow To Benchmark Disk I/O
Here is a quick snipped on how to benchmark Disk I/O with dd.
time sh -c "dd if=/dev/zero of=/home/rchapin/test.zeros bs=1024k count=10000 && sync"
10000+0 records in
10000+0 records out
10485760000 bytes (10 GB) copied, 81.4124 s, 129 MB/s
real 1m21.950s
user 0m0.810s
sys 0m5.474sWill do a write test of 10GB.
You can do a similar test and read from that file generated and write to another file or /dev/null to get an idea of the read speeds.
Creating an Array in Bash from a File With Each Element on a Separate Line
Let’s say that you have a file and you would like to convert each line in the file to an element in an array.
The key to this is knowing about and how to manipulate the IFS (Internal Field Separator). The default IFS is whitespace (a space, tab, or newline) and if you create an array passing it a whitespace delimited list of strings, each token will be set to an element in the array.
ARRAY=(a b d Installing Chrome Extensions Without Signing in With a Google Account
Google requires that you login with a Google account before you can install any Chrome extensions.
The following is how to install an extension without logging in (under Windows. The same should work under Linux and Mac):
- Find the ID for the extension. When you browse the extension in the store you will see a URL similar to the following: https://chrome.google.com/webstore/detail/cookies/iphcomljdfghbkdcfndaijbokpgddeno?hl=en. The hash string after the ‘cookies’ string (the name of the extension) up to the ? is the
Removing The Last N Character From a String in Bash Script with sed
Here is a quick one-liner for trimming a specific number of characters from the end of a string under bash:
# Remove the last 5 characters
$ echo "somestringwith12345" | sed "s/.....$//g"
$ somestringwith
# Remove the last 3 characters
$ echo "somestringwith12345" | sed "s/...$//g"
$ somestringwith12Running Multiple Instances of Notepad++ Under Windows 7
If you want to run multiple versions of Notepad++ under Windows 7 create a .bat file with the following:
"C:\Program Files (x86)\Notepad++\notepad++.exe" -multiInst %1And simply run the bat file via a cmd prompt/ → Continue reading “Running Multiple Instances of Notepad++ Under Windows 7”