Ubuntu – Add a string to a text file from terminal

bashcommand line

I would like to modify a bunch of text files from the terminal, more precisey:

add the string '50' to the first line of every text file in /mydat/ ?

Alternatively, if you know of a link to a page on the web that lists commands to manipulate text files from the shell…

Best Answer

find and sed are your weapons of choice:

find /mydat/ -exec sed '1i 50' {} \;

That will stick 50 followed by a new line on the beginning of the file.

Alternatively if you don't need recursion or complex selectors for find you can drop find completely:

sed '1i 50' *

Related Solutions

Ubuntu – Add words to a text file using a single terminal command (no editors)

I usually do this way when I am programming my script to do same what you are asking but programmatically.

echo "Hello you!" >> myfile.txt
echo "this is 2nd line text" >> file.txt
echo "last line!" >> file.txt

Voila! You got it. Important to note >> means adding new line to existing file meanwhile > just simply overwrite everything.

Ubuntu – How to run commands from a bash file the way they run from terminal

Consider this script (saved as /home/muru/test.sh):

#! /bin/bash
DRI_PRIME=1 glxgears -info

A basic launcher for this would look like (say, save it as /home/muru/test.desktop):

[Desktop Entry]
Type=Application
Terminal=true
Name=glx-gears-info
Exec=/home/muru/test.sh

Make them both executable:

chmod +x test.sh test.desktop

Now you should have these two entries in your home folder: enter image description here

Notice how the name is glx-gears-info even though the launcher's filename is test.desktop. You can double click on it to start the script: enter image description here

For a script like (say, located at /home/muru/start-aria.sh):

#!/bin/bash
touch /home/cip/Downloads/aria2/session.txt && \
    aria2c --enable-rpc --rpc-listen-all \
       --save-session=/home/cip/Downloads/aria2/session.txt \
       --input-file=/home/cip/Downloads/aria2/session.txt -x16 -s16 -k1M \
       --dir=/home/cip/Downloads/aria2

(I split the command into multiple lines for readability) the launcher file would look like (say /home/muru/start-aria.desktop):

[Desktop Entry]
Type=Application
Terminal=false
Name=Start Aria2
Exec=/home/muru/start-aria.sh

You can set Terminal=false here as this command probably doesn't need a terminal.

To get the terminal window when using Xfce launchers, tick 'Run in Terminal'.

enter image description here

A second command, that would close aria2, can be added in the same Xfce launcher: pkill aria2c

Also:

by adding them into a single launcher,
setting advanced properties like in the image below

enter image description here

(namely 'show last used item' and 'inside button'),

and adding two specific icons,

the launcher will always display the current status of aria2: running or closed.

enter image description here

Best Answer

Related Solutions

Ubuntu – Add words to a text file using a single terminal command (no editors)

Ubuntu – How to run commands from a bash file the way they run from terminal

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