General :: Does The Output Of The Previous Command Get Stored In Any Variable
Mar 26, 2011
For example, when using bash you can use
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to execute the previous command or
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!<number> to execute the Nth command(use history to see the list). Or you can use
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cd !-2:1
to cd into the value in the first field that was executed 2 commands ago Anyhow, say I run a command and the output is a path. Any way to cd and then some variable where OUTPUT of the previous command was stored? A variable that always stores the OUTPUT of the last command.
I want to use the output of a previous command as a parameter to another command. For example: to know where "nice" is stored i typed: which nice output: /usr/bin/nice now the second command i typed is: ls -l /usr/bin/nice Is there a way to have a single command like: ls -l which nice ?
I tried using the tail command in my shell script and storing that value in a variable a but an error keeps coming. Is there any other way to store the output of a command into a variable. Cannot Read text from text file and store it in a variable using shell script. The thing is I need a number from the file new.txt and use that number in my script
#!/bin/bash a = `tail -1 new.txt|head -n 1` echo $a
Suppose I want to account number of files beginning with abc , I can use "ls 'abc* | grep abc | wc -l", this will return me a number. I want to store this number in a variable, say var1, so I tried 1. "ls 'abc* | grep abc | wc -l |read var1", but this didn't work as var1 has no value somehow. 2. var1='ls 'abc* | grep abc | wc -l', this just assign the entire string "ls 'abc* | grep abc | wc -l" to var1, which is not I wanted.
I don't want to store the value to a temporary file and then read the value from that file. I think there should be a direct way to get the value, but don't know how. I know in tcsh, one can just use set var1='ls 'abc* | grep abc | wc -l', but it also doesn't work in bash. Can anyone give any clue about this?
run_repeatedly "programX -o "./messy/path/output-$NUM.txt"" The echo inside the loop prints "...-$NUM.txt"; obviously I'm aiming to have bash substitute the iteration number so that I end up with many output files not 1.
I know how to redirect the output of a terminal to a file. For example, if I want to list all the files in ~/Documents and output to a file called test.txt, I would do this: ls ~/Documents > test.txt The question is, can I copy the output to test.txt AFTER I have carried out the command? This would mean that I wouldn't have to know in advance whether I want to copy the output to file. I want to do something like this: ls ~/Documents Then this: <bash command for copying standard output to test.txt>
For example, I run a program called "luck" and it outputs a sentence like "good luck". Then "./luck -> logfile" will save the output content to logfile.But when I run another program called "hello" and it outputs a sentence lie " Hello world".Then "./hello-> logfile" will save the output content to logfile and wipe the previous contents.Is is possible to keep both sentences in the logfile? Just like
i'm trying to redirect the output of a command to the input of the next command. not sure if i'm going about this the right way. an easy method would be just to store the output of the previous command in a file and redirect input to read that file, but i'm curious to see if this can be done without writing to any files.
In my script, I need to get execution time of a command (say 'ls') in mili seconds level. For this i tried using "time" command to retrieve the total execution time in milli seconds. But, the problem is that, how to save the output of time command in a variable. The format of the command is like "time ls -R /opt" Going further, the o/p of 'time' command is:
real 0m0.003s user 0m0.004s sys 0m0.000s
Here, in my script, I would like to use only middle line "user 0m0.004s" saved to the variable but unable to find out the way.
I am having some weird problems with calling commands stored in a variable (I need to do this to assemble a command with a bunch of parameters automatically and then execute it).Example code that will replicate the weirdness:
What happens to the quotes? I have tried various combinations of single quotes, escaped quotes, etc, but it seems like quotes in a variable are not evaluated as quotes when that variable is executed.
I would like to grep two numbers out of a text file, and divide them.
Here is the script code...
It feels like grep saves a new line too? or what is happening? i simply can't divide them, as it handles the variables as they are empty (and prints the two numbers although they were not printed
Allow me to submit that i did a mistake of not saving the work which i done in the past few months. i have used history command to see the previous commands. But trouble is that since i had worked a lot on gnome-terminal, only last 1000 commands are shown. Is it possible to see list of all the previous commands for all users. Also, sorry if this sounds absurd, but is it possible to save the details of a session onto a single file ? I not sure but when i had worked on vector Linux, i had used some command to save sessions at the terminal. Is there any analogous command in Ubuntu 10.04 also ?
I have enabled usb storage debug prints for the debugging of my driver in kernel 2.6.24.4 of Fedora 8. When I type dmesg and press enter I see many prints on the screen. There are however lot many prints and I want all those prints from the beginning. However it seems that the older prints are overwritten with newer prints. SO if just redirect the dmesg output to some file, I get only newest prints but older are lost.
Surprisingly /var/log/messages doesn't contain those prints! Also I see there is a file named /var/log/dmesg , but that files never gets updated with the prints I see on the screen. So, my question is can I get all those dmesg prints right from the beginning in a file somewhere?
i need to count the number of files and put the output into a variable. i used wc -l filename but i couldnt find an option to put the output to variable. example if the number o line is 5, i need the output of echo $x is 5.
I need to create a single line of output from multiple and variable lines of input in a Linux bash shell script.
My input file looks like this:
Where there may be any number of umsecondaryphonenumber lines; if there is not a umsecondaryphonenumber line for a telephonenumber, I don't want to write any output.
So, the output file should look like:
The script I have so far is:
My question is - how do print each of the elements of an array in one record - i.e. what do I put in place of howdoiprintarray?
I am using openSUSE 10.3.When I install software from tarball then to record time required I send output of date to beg.txt(when installation begins) and end.txt (when installation finishes).How can I append output of date to a file so I don't need two files?
I want to run gsettings list-schemas (which return a list of about 100 names separated by spaces)and somehow direct each name one at a time as the input to this command:gsettings list-recursivelyI've tried it with awk, and standard | piping and also as a string variable strvar=$(gsettings list-schemas) and using the $strvar as the input butam missing something in between I'm sure like for - while or proper syntax of awk etc
I would like to access/print a C Variable of any type "as it is stored in the memory". I would expect the output to be an array of bits. Whats the simplest/shortest way to do that?
I was reading that if I want to do a one time scheduled command, I should use at, which I've never done, as opposed to cron, which i'm kinda familiar with. But what I want to do is reboot my server at 3am tomorrow and force it to check the file systems with a shutdown -rF. For this do I even need to use "at" or could I just say shutdown -rF 3:00.Will that also know that I mean 3am tomorrow and not say in 3 minutes from now or 3pm?
When I run this command from shell, it runs ok export REVS=`svn info svn+ssh://svn.myone.ca/var/svn/story/trunk/lib |grep 'Last Changed Rev:'| awk -F: '{print $2}'` However when I save it into a file called test.sh (of course, I chmod it with +x), I got error "export: 2: bad variable name"
Here is the file: #!/bin/bash export REVS=`svn info svn+ssh://svn.myone.ca/var/svn/story/trunk/lib |grep 'Last Changed Rev:'| awk -F: '{print $2}'` I am using ubuntu.
I am using CentOS5.5 & everytime it is showing command not found. If I export the path as below it will be working fine until a reboot. Again same error i.e command not found if I open new terminal. Every time I am exporting as below:
How can I set these permanently as that the paths should automatically be exported for everyone user whenever the system boots. And command completion also should happen for eg. #fdi (press tab), then it should show available options such as fdisk, etc.
