I'm currently implementing the execv syscall into my own kernel. However, I managed to calculate the argument count(argc) in user space and passed argc and argv to my kernel exec function via a system call.
Actually, I don't know how to pass these two variables now to the new user threads main function. I allocated a new stack page and stored argc and argv in sequence onto this page space. My I idea was to point either EDI or ESI user register to the first argument (argc) followed by the argv array.
I'm not sure if it is correct to use EDI or ESI for this purpose. Does anybody know how the arguments get passed inside other kernels?
You need to setup the user stack properly and then the entry point of the ELF executable would be responsible for locating argc and argv on the stack. The function in the Linux kernel responsible for seting up the stack is create_elf_tables. For a visual representation, you can check out this nice figure from this great LWN.net article:
------------------------------------------------------------- 0x7fff6c845000
0x7fff6c844ff8: 0x0000000000000000
_ 4fec: './stackdump\0' <------+
env / 4fe2: 'ENVVAR2=2\0' | <----+
\_ 4fd8: 'ENVVAR1=1\0' | <---+ |
/ 4fd4: 'two\0' | | | <----+
args | 4fd0: 'one\0' | | | <---+ |
\_ 4fcb: 'zero\0' | | | <--+ | |
3020: random gap padded to 16B boundary | | | | | |
- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -| | | | | |
3019: 'x86_64\0' <-+ | | | | | |
auxv 3009: random data: ed99b6...2adcc7 | <-+ | | | | | |
data 3000: zero padding to align stack | | | | | | | |
. . . . . . . . . . . . . . . . . . . . . . . . . . .|. .|. .| | | | | |
2ff0: AT_NULL(0)=0 | | | | | | | |
2fe0: AT_PLATFORM(15)=0x7fff6c843019 --+ | | | | | | |
2fd0: AT_EXECFN(31)=0x7fff6c844fec ------|---+ | | | | |
2fc0: AT_RANDOM(25)=0x7fff6c843009 ------+ | | | | |
ELF 2fb0: AT_SECURE(23)=0 | | | | |
auxiliary 2fa0: AT_EGID(14)=1000 | | | | |
vector: 2f90: AT_GID(13)=1000 | | | | |
(id,val) 2f80: AT_EUID(12)=1000 | | | | |
pairs 2f70: AT_UID(11)=1000 | | | | |
2f60: AT_ENTRY(9)=0x4010c0 | | | | |
2f50: AT_FLAGS(8)=0 | | | | |
2f40: AT_BASE(7)=0x7ff6c1122000 | | | | |
2f30: AT_PHNUM(5)=9 | | | | |
2f20: AT_PHENT(4)=56 | | | | |
2f10: AT_PHDR(3)=0x400040 | | | | |
2f00: AT_CLKTCK(17)=100 | | | | |
2ef0: AT_PAGESZ(6)=4096 | | | | |
2ee0: AT_HWCAP(16)=0xbfebfbff | | | | |
2ed0: AT_SYSINFO_EHDR(33)=0x7fff6c86b000 | | | | |
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . | | | | |
2ec8: environ[2]=(nil) | | | | |
2ec0: environ[1]=0x7fff6c844fe2 ------------------|-+ | | |
2eb8: environ[0]=0x7fff6c844fd8 ------------------+ | | |
2eb0: argv[3]=(nil) | | |
2ea8: argv[2]=0x7fff6c844fd4 ---------------------------|-|-+
2ea0: argv[1]=0x7fff6c844fd0 ---------------------------|-+
2e98: argv[0]=0x7fff6c844fcb ---------------------------+
0x7fff6c842e90: argc=3
At the first instruction of the entry point of the ELF binary (glibc calls it _start), the top of the stack (0(%rsp)) would point to argc, as shown in the figure. Then follows the argv array, which is just an array of pointers. The environment variables array is also part of the ABI, as well as the ELF auxiliary vector (which may be used by the glibc initialization code). Although if you know for sure (or assume) that the ELF binary is not going to use the environment variables array or the auxiliary vector, then you just setup argv and argc as shown in the figure.
Related
My file looks as follows:
+------------------------------------------+---------------+----------------+------------------+------------------+-----------------+
| Message | Status | Adress | Changes | Test | Calibration |
|------------------------------------------+---------------+----------------+------------------+------------------+-----------------|
| Hello World | Active | up | 1 | up | done |
| Hello Everyone Here | Passive | up | 2 | down | none |
| Hi there. My name is Eric. How are you? | Down | up | 3 | inactive | done |
+------------------------------------------+---------------+----------------+------------------+------------------+-----------------+
+----------------------------+---------------+----------------+------------------+------------------+-----------------+
| Message | Status | Adress | Changes | Test | Calibration |
|----------------------------+---------------+----------------+------------------+------------------+-----------------|
| What's up? | Active | up | 1 | up | done |
| Hi. I'm Otilia | Passive | up | 2 | down | none |
| Hi there. This is Marcus | Up | up | 3 | inactive | done |
+----------------------------+---------------+----------------+------------------+------------------+-----------------+
I want to extract a specific column using AWK.
I can use CUT to do it; however when the length of each table varies depending on how many characters are present in each column, I'm not getting the desired output.
cat File.txt | cut -c -44
+------------------------------------------+
| Message |
|------------------------------------------+
| Hello World |
| Hello Everyone Here |
| Hi there. My name is Eric. How are you? |
+------------------------------------------+
+----------------------------+--------------
| Message | Status
|----------------------------+--------------
| What's up? | Active
| Hi. I'm Otilia | Passive
| Hi there. This is Marcus | Up
+----------------------------+--------------
or
cat File.txt | cut -c 44-60
+---------------+
| Status |
+---------------+
| Active |
| Passive |
| Down |
+---------------+
--+--------------
| Adress
--+--------------
| up
| up
| up
--+--------------
I tried using AWK but I don't know how to add 2 different delimiters which would take care of all the lines.
cat File.txt | awk 'BEGIN {FS="|";}{print $2,$3}'
Message Status
------------------------------------------+---------------+----------------+------------------+------------------+-----------------
Hello World Active
Hello Everyone Here Passive
Hi there. My name is Eric. How are you? Down
Message Status
----------------------------+---------------+----------------+------------------+------------------+-----------------
What's up? Active
Hi. I'm Otilia Passive
Hi there. This is Marcus Up
The output I'm looking for:
+------------------------------------------+
| Message |
|------------------------------------------+
| Hello World |
| Hello Everyone Here |
| Hi there. My name is Eric. How are you? |
+------------------------------------------+
+----------------------------+
| Message |
|----------------------------+
| What's up? |
| Hi. I'm Otilia |
| Hi there. This is Marcus |
+----------------------------+
or
+------------------------------------------+---------------+
| Message | Status |
|------------------------------------------+---------------+
| Hello World | Active |
| Hello Everyone Here | Passive |
| Hi there. My name is Eric. How are you? | Down |
+------------------------------------------+---------------+
+----------------------------+---------------+
| Message | Status |
|----------------------------+---------------+
| What's up? | Active |
| Hi. I'm Otilia | Passive |
| Hi there. This is Marcus | Up |
+----------------------------+---------------+
or random other columns
+------------------------------------------+----------------+------------------+
| Message | Adress | Test |
|------------------------------------------+----------------+------------------+
| Hello World | up | up |
| Hello Everyone Here | up | down |
| Hi there. My name is Eric. How are you? | up | inactive |
+------------------------------------------+----------------+------------------+
+----------------------------+---------------+------------------+
| Message |Adress | Test |
|----------------------------+---------------+------------------+
| What's up? |up | up |
| Hi. I'm Otilia |up | down |
| Hi there. This is Marcus |up | inactive |
+----------------------------+---------------+------------------+
Thanks in advance.
One idea using GNU awk:
awk -v fldlist="2,3" '
BEGIN { fldcnt=split(fldlist,fields,",") } # split fldlist into array fields[]
{ split($0,arr,/[|+]/,seps) # split current line on dual delimiters "|" and "+"
for (i=1;i<=fldcnt;i++) # loop through our array of fields (fldlist)
printf "%s%s", seps[fields[i]-1], arr[fields[i]] # print leading separator/delimiter and field
printf "%s\n", seps[fields[fldcnt]] # print trailing separator/delimiter and terminate line
}
' File.txt
NOTES:
requires GNU awk for the 4th argument to the split() function (seps == array of separators; see gawk string functions for details)
assumes our field delimiters (|, +) do not show up as part of the data
the input variable fldlist is a comma-delimited list of columns that mimics what would be passed to cut (eg, when a line starts with a delimiter then field #1 is blank)
For fldlist="2,3" this generates:
+------------------------------------------+---------------+
| Message | Status |
|------------------------------------------+---------------+
| Hello World | Active |
| Hello Everyone Here | Passive |
| Hi there. My name is Eric. How are you? | Down |
+------------------------------------------+---------------+
+----------------------------+---------------+
| Message | Status |
|----------------------------+---------------+
| What's up? | Active |
| Hi. I'm Otilia | Passive |
| Hi there. This is Marcus | Up |
+----------------------------+---------------+
For fldlist="2,4,6" this generates:
+------------------------------------------+----------------+------------------+
| Message | Adress | Test |
|------------------------------------------+----------------+------------------+
| Hello World | up | up |
| Hello Everyone Here | up | down |
| Hi there. My name is Eric. How are you? | up | inactive |
+------------------------------------------+----------------+------------------+
+----------------------------+----------------+------------------+
| Message | Adress | Test |
|----------------------------+----------------+------------------+
| What's up? | up | up |
| Hi. I'm Otilia | up | down |
| Hi there. This is Marcus | up | inactive |
+----------------------------+----------------+------------------+
For fldlist="4,3,2" this generates:
+----------------+---------------+------------------------------------------+
| Adress | Status | Message |
+----------------+---------------|------------------------------------------+
| up | Active | Hello World |
| up | Passive | Hello Everyone Here |
| up | Down | Hi there. My name is Eric. How are you? |
+----------------+---------------+------------------------------------------+
+----------------+---------------+----------------------------+
| Adress | Status | Message |
+----------------+---------------|----------------------------+
| up | Active | What's up? |
| up | Passive | Hi. I'm Otilia |
| up | Up | Hi there. This is Marcus |
+----------------+---------------+----------------------------+
Say that again? (fldlist="3,3,3"):
+---------------+---------------+---------------+
| Status | Status | Status |
+---------------+---------------+---------------+
| Active | Active | Active |
| Passive | Passive | Passive |
| Down | Down | Down |
+---------------+---------------+---------------+
+---------------+---------------+---------------+
| Status | Status | Status |
+---------------+---------------+---------------+
| Active | Active | Active |
| Passive | Passive | Passive |
| Up | Up | Up |
+---------------+---------------+---------------+
And if you make the mistake of trying to print the '1st' column, ie, fldlist="1":
+
|
|
|
|
|
+
+
|
|
|
|
|
+
If GNU awk is available, please try markp-fuso's nice solution.
If not, here is a posix-compliant alternative:
#!/bin/bash
# define bash variables
cols=(2 3 6) # bash array of desired columns
col_list=$(IFS=,; echo "${cols[*]}") # create a csv string
awk -v cols="$col_list" '
NR==FNR {
if (match($0, /^[|+]/)) { # the record contains a table
if (match($0, /^[|+]-/)) # horizontally ruled line
n = split($0, a, /[|+]/) # split into columns
else # "cell" line
n = split($0, a, /\|/)
len = 0
for (i = 1; i < n; i++) {
len += length(a[i]) + 1 # accumulated column position
pos[FNR, i] = len
}
}
next
}
{
n = split(cols, a, /,/) # split the variable `cols` on comma into an array
for (i = 1; i <= n; i++) {
col = a[i]
if (pos[FNR, col] && pos[FNR, col+1]) {
printf("%s", substr($0, pos[FNR, col], pos[FNR, col + 1] - pos[FNR, col]))
}
}
print(substr($0, pos[FNR, col + 1], 1))
}
' file.txt file.txt
Result with cols=(2 3 6) as shown above:
+---------------+----------------+-----------------+
| Status | Adress | Calibration |
+---------------+----------------+-----------------|
| Active | up | done |
| Passive | up | none |
| Down | up | done |
+---------------+----------------+-----------------+
+---------------+----------------+-----------------+
| Status | Adress | Calibration |
+---------------+----------------+-----------------|
| Active | up | done |
| Passive | up | none |
| Up | up | done |
+---------------+----------------+-----------------+
It detects the column width in the 1st pass then splits the line on the column position in the 2nd pass.
You can control the columns to print with the bash array cols which is assigned at the beginning of the script. Please assign the array to the list of desired column numbers in increasing order. If you want to use the bash variable in different way, please let me know.
In a project where XML/JS/Java files can contain references to other such files, I'd like to be able to have a quick overview of what has to be carefully checked, when one file has been updated.
So, it means I need to eventually have a look at all files referencing the modified one, and all files referencing files which refer to the modified one, etc. (recursively on matched files).
For one level, it's quite simple:
grep -E -l -o --include=*.{xml,js,java} -r "$FILE" . | xargs -n 1 basename
But how can I automate that to match (grand-(grand-))parents?
And how can that be, maybe, made more readable? For example, with a tree structure?
For example, if the file that interests me is called modified.js...
show-referring-files-to modified.js
... I could wish such an output:
some-file-with-ref-to-modified.xml
|__ a-file-referring-to-some-file-with-ref-to-modified.js
another-one-with-ref-to-modified.xml
|__ a-file-referring-to-another-one-with-ref-to-modified.js
|__ a-grand-parent-file-having-ref-to-ref-file.xml
|__ another-file-referring-to-another-one-with-ref-to-modified.js
or any other output (even flat) which allows for quickly checking which files are potentially impacted by a change.
UPDATE -- Results of current proposed answer:
ahmsff.js
|__ahmsff.xml
| |__ahmsd.js
| | |__ahmsd.xml
| | | |__ahmst.xml
| | | | |__BESH.java
| |__ahru.js
| | |__ahru.xml
| | | |__ahrut.xml
| | | | |__ashrba.js
| | | | | |__ashrba.xml
| | | | | | |__STR.java
| | |__ahrufrp.xml
| | | |__ahru.js
| | | | |__ahru.xml
| | | | | |__ahrut.xml
| | | | | | |__ashrba.js
| | | | | | | |__ashrba.xml
| | | | | | | | |__STR.java
| | | | |__ahrufrp.xml
| | | | | |__ahru.js
| | | | | | |__ahru.xml
| | | | | | | |__ahrut.xml
| | | | | | | | |__ashrba.js
| | | | | | | | | |__ashrba.xml
| | | | | | | | | | |__STR.java
| | | | | | |__ahrufrp.xml
(...)
I'd use a shell function (for the recursion) inside an shell script:
Assuming the filenames are unique have no characters that need escaping in them:
File: /usr/local/bin/show-referring-files-to
#!/bin/sh
get_references() {
grep -F -l --include=*.{xml,js,java} -r "$1" . | grep -v "$3" | while read -r subfile; do
#read each line of the grep result into the variable subfile
subfile="$(basename "$subfile")"
echo "$2""$subfile"
get_references "$subfile" ' '"$2" "$3"'\|'"$subfile"
done
}
while test $# -gt 0; do
#loop so more than one file can be given as argument to this script
echo "$1"
get_references "$1" '|__' "$1"
shift
done
There still are lots of performance enhancements possible.
Edit: Added $3 to prevent infinite-loop.
My folder structure with 2000 folder and every folder having 2000 csv file(every csv file size:upto 3KB).
But my problem is when i copy paste whole folder to other place it takes about 6 hours.
So i need to minimize that time using batch file.I want to know why it takes like this much and any idea to solve this problem.
data
|-----LrK90001
| |----LrK90001.csv
| |----LrK90001_e.csv
| |----LrK90002.csv
| |----LrK90002_e.csv
| .
| .
| .
| |----LrK91000_e.csv
|
|-----LrK90002
| |----LrK90001.csv
| |----LrK90001_e.csv
| |----LrK90002.csv
| |----LrK90002_e.csv
| .
| .
| .
| |----LrK91000_e.csv
.
.
.
|-----LrK92000
| |----LrK90001.csv
| |----LrK90001_e.csv
| |----LrK90002.csv
| |----LrK90002_e.csv
| .
| .
| .
| |----LrK91000_e.csv
|
My pc spec:
Processor - Intel i5
RAM - 16GB
I want to check whether a given user has access to a given folder - by checking if they have "Modify" access assigned to them.
I thought that the PS for that would be:
(Get-Acl .\myfolder).Access | ?{$_.IdentityReference -eq "BUILTIN\Users"} |?{$_.filesystemrights.value -contains "Modify"}
But the final part of that isn't working - I get back no result. But I know that they have Modify access - if I put in:
(Get-Acl .\myfolder).Access | ?{$_.IdentityReference -eq "BUILTIN\Users"} | select -ExpandProperty filesystemrights
then I get back:
Modify, Synchronize
ReadAndExecute, Synchronize
Is this because the FileSystemRights property is an enumeration? And if so, how do I test against it?
It's a type problem. (Get-Acl .\myfolder).Access[].FileSystemRights is of type System.Security.AccessControl.FileSystemRights. It's not really displaying a string. To make it a string, just use the ToString() method:
(Get-Acl .\myfolder).Access | ?{$_.IdentityReference -eq "BUILTIN\Users"} |?{$_.filesystemrights.ToString() -contains "Modify"}
Or you can use the bitwise comparison method. However, it's very easy to confuse when you want to use this:
($_.FileSystemRights -band [System.Security.AccessControl.FileSystemRights]::Modify) -eq [System.Security.AccessControl.FileSystemRights]::Modify
With when you want to use this:
($_.FileSystemRights -band [System.Security.AccessControl.FileSystemRights]::Modify) -eq $_.FileSystemRights
They have very different meanings. For example, if you have Full Control, the former test is still true. Is that what you want? Or do you want to know when the FileSystemRights are literally just Modify?
Also, [System.Security.AccessControl.FileSystemRights] is an incomplete enumeration. In my environment, I found I needed this table:
+-------------+------------------------------+------------------------------+
| Value | Name | Alias |
+-------------+------------------------------+------------------------------+
| -2147483648 | GENERIC_READ | GENERIC_READ |
| 1 | ReadData | ListDirectory |
| 1 | ReadData | ReadData |
| 2 | CreateFiles | CreateFiles |
| 2 | CreateFiles | WriteData |
| 4 | AppendData | AppendData |
| 4 | AppendData | CreateDirectories |
| 8 | ReadExtendedAttributes | ReadExtendedAttributes |
| 16 | WriteExtendedAttributes | WriteExtendedAttributes |
| 32 | ExecuteFile | ExecuteFile |
| 32 | ExecuteFile | Traverse |
| 64 | DeleteSubdirectoriesAndFiles | DeleteSubdirectoriesAndFiles |
| 128 | ReadAttributes | ReadAttributes |
| 256 | WriteAttributes | WriteAttributes |
| 278 | Write | Write |
| 65536 | Delete | Delete |
| 131072 | ReadPermissions | ReadPermissions |
| 131209 | Read | Read |
| 131241 | ReadAndExecute | ReadAndExecute |
| 197055 | Modify | Modify |
| 262144 | ChangePermissions | ChangePermissions |
| 524288 | TakeOwnership | TakeOwnership |
| 1048576 | Synchronize | Synchronize |
| 2032127 | FullControl | FullControl |
| 268435456 | GENERIC_ALL | GENERIC_ALL |
| 536870912 | GENERIC_EXECUTE | GENERIC_EXECUTE |
| 1073741824 | GENERIC_WRITE | GENERIC_WRITE |
+-------------+------------------------------+------------------------------+
It's interesting to compare the output of these:
[System.Enum]::GetNames([System.Security.AccessControl.FileSystemRights]);
[System.Enum]::GetNames([System.Security.AccessControl.FileSystemRights]) | % { "$($_.ToString())`t`t$([System.Security.AccessControl.FileSystemRights]$_.ToString())`t`t$(([System.Security.AccessControl.FileSystemRights]$_).value__)";}
[System.Enum]::GetValues([System.Security.AccessControl.FileSystemRights]) | % { "$($_.ToString())`t`t$(($_).value__)";}
The GENERIC rights are not enumerated in the .Net class, but you will see that numeric value if you enumerate enough files.
Good luck!
Got it:
(get-acl .\myfolder).Access | ?{$_.IdentityReference -eq "BUILTIN\Users"} | ?{($_.FileSystemRights -band [System.Security.AccessControl.FileSystemRights]::Modify) -eq [System.Security.AccessControl.FileSystemRights]::Modify}
It's both a bitwise comparison - and therefore you need to use "-band".
But "-band" will return true if any of the same bits are set in both enumerations. And as even "Read" has several bits set (it's 100000000010001001) - some of which will match with "Modify", you need to also compare the result with "Modify" to make sure that the result is actually the same.
(Thanks to the comments below for getting me pointed in the right direction.)
Updated new version.
Clarified version from Arco's comment.
With this version we're checking if the Modify bit is set.
(Get-Acl .\myfolder).Access | ?{$_.IdentityReference -eq "BUILTIN\Users"} |?{ $_.FileSystemRights -band [Security.AccessControl.FileSystemRights]::Modify}
The value__ property is the numeric bit set version.
I've got the following problem:
There is a Postgres database which I need to get data from, via a Nagios Linux distribution.
My intention is to make a resulting SELECT be saved to a .txt, that would be sent via email to me using MUTT.
Until now, I've done:
#!/bin/sh
psql -d roaming -U thdroaming -o saida.txt << EOF
\d
\pset border 2
SELECT central, imsi, mapver, camel, nrrg, plmn, inoper, natms, cba, cbaz, stall, ownms, imsi_translation, forbrat FROM vw_erros_mgisp_totalizador
EOF
My problem is:
The .txt "saida.txt" is bringing me info about the database, as follows:
Lista de relações
Esquema | Nome | Tipo | Dono
---------+----------------------------------+-----------+------------
public | apns | tabela | jmsilva
public | config_imsis_centrais | tabela | thdroaming
public | config_imsis_sgsn | tabela | postgres
(3 Registers)
+---------+---------+----------+---------+---------+--------+------------+-------+---------+----------+-------+-------+------------------+-----------+
| central | imsi | mapver | camel | nrrg | plmn | inoper | natms | cba | cbaz | stall | ownms | imsi_translation | forbrat |
+---------+---------+----------+---------+---------+--------+------------+-------+---------+----------+-------+-------+------------------+-----------+
| MCTA02 | 20210 | | | | | INOPER-127 | | | | | | | |
| MCTA02 | 20404 | | | | | INOPER-127 | | | | | | | |
| MCTA02 | 20408 | | | | | INOPER-127 | | | | | | | |
| MCTA02 | 20412 | | | | | INOPER-127 | | | | | | | |
.
.
.
How could I make the first table not to be imported to the .txt?
Remove the '\d' portion of the script which causing listing the tables in the DB you see at the top of your output. So your script will become:
#!/bin/sh
psql -d roaming -U thdroaming -o saida.txt << EOF
\pset border 2
SELECT central, imsi, mapver, camel, nrrg, plmn, inoper, natms, cba, cbaz, stall, ownms, imsi_translation, forbrat FROM vw_erros_mgisp_totalizador
EOF
To get the output to appear CSV formatted in a file named /tmp/output.csv do you can do the following:
#!/bin/sh
psql -d roaming -U thdroaming -o saida.txt << EOF
\pset border 2
COPY (SELECT central, imsi, mapver, camel, nrrg, plmn, inoper, natms, cba, cbaz, stall, ownms, imsi_translation, forbrat FROM vw_erros_mgisp_totalizador) TO '/tmp/output.csv' WITH (FORMAT CSV)
EOF