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https://github.com/megamansec/body
Print the middle lines of files. It's not cat, tail, or head: it's body.
https://github.com/megamansec/body
Last synced: 5 days ago
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Print the middle lines of files. It's not cat, tail, or head: it's body.
- Host: GitHub
- URL: https://github.com/megamansec/body
- Owner: MegaManSec
- Created: 2024-02-02T07:21:35.000Z (11 months ago)
- Default Branch: main
- Last Pushed: 2024-03-03T09:22:56.000Z (10 months ago)
- Last Synced: 2024-11-09T09:40:37.098Z (2 months ago)
- Language: Shell
- Size: 8.79 KB
- Stars: 2
- Watchers: 2
- Forks: 0
- Open Issues: 0
-
Metadata Files:
- Readme: README.md
Awesome Lists containing this project
README
_body_: print the middle line(s) of files.
`body [-B ] [-A ] [-C ] [-n] [-N] `
parameters:
-B[number]: print _number_ lines before the middle line.
-A[number]: print _number_ lines after the middle line.
-C[number]: print _number_ lines before and after the middle line.
-n: do not print the line number(s), just print the contents of the line(s).
-N: do not print the file name (only utilized if multiple files filenames are specified).
filename: file to parse. can be specified multiple times. if multiple files are specified, the file name is also printed.
by default, only the middle line is shown.
examples:
```bash
$ body /etc/passwd /etc/group
/etc/passwd:65:_dpaudio:*:215:215:DP Audio:/var/empty:/usr/bin/false
/etc/group:79:_atsserver:*:97:
$ body -A3 -B1 /etc/passwd /etc/group
/etc/passwd:64:_dovecot:*:214:6:Dovecot Administrator:/var/empty:/usr/bin/false
/etc/passwd:65:_dpaudio:*:215:215:DP Audio:/var/empty:/usr/bin/false
/etc/passwd:66:_postgres:*:216:216:PostgreSQL Server:/var/empty:/usr/bin/false
/etc/passwd:67:_krbtgt:*:217:-2:Kerberos Ticket Granting Ticket:/var/empty:/usr/bin/false
/etc/passwd:68:_kadmin_admin:*:218:-2:Kerberos Admin Service:/var/empty:/usr/bin/false
/etc/group:78:_installer:*:96:
/etc/group:79:_atsserver:*:97:
/etc/group:80:_lpadmin:*:98:
/etc/group:81:_unknown:*:99:
/etc/group:82:_lpoperator:*:100:
$ body -C1 /etc/passwd
64:_dovecot:*:214:6:Dovecot Administrator:/var/empty:/usr/bin/false
65:_dpaudio:*:215:215:DP Audio:/var/empty:/usr/bin/false
66:_postgres:*:216:216:PostgreSQL Server:/var/empty:/usr/bin/false
```
---
benchmarks:
given the following test file:
```bash
#!/bin/bash
file="/var/log/auth.log.1"
benchmark_command() {
local start_time=$(date +%s.%N)
for i in {1..20}; do
eval "$1" >/dev/null
echo 3 > /proc/sys/vm/drop_caches
done
local end_time=$(date +%s.%N)
local elapsed_time=$(echo "$end_time - $start_time" | bc -l)
local average_time=$(echo "$elapsed_time / 10" | bc -l)
printf "%.6f " "$average_time"
}
echo 3 > /proc/sys/vm/drop_caches
benchmark_command "lines=\$(wc -l < $file); lines=\$((lines/2)); head -n\$lines $file | tail -n1"
benchmark_command "lines=\$(wc -l < $file); lines=\$((lines/2)); cat -n $file | head -n\$lines | tail -n1"
benchmark_command "lines=\$(wc -l < $file); lines=\$((lines/2)); sed \$lines,\$lines'!d;=' $file | sed 'N;s/\\n/ /'"
benchmark_command "lines=\$(wc -l < $file); lines=\$((lines/2)); awk 'NR==$lines{print NR\" \"\$0}' $file"
benchmark_command "lines=\$(wc -l < $file); lines=\$((lines/2)); cat -n $file | sed -n \$lines,\${lines}p"
echo
```
executed 20 times, the results come out as:
```bash
for i in {1..20}; do bash /tmp/test; done | awk '{
for (i = 1; i <= NF; i++) {
sum[i] += $i
count[i]++
}
}
END {
for (i = 1; i <= NF; i++) {
printf "avg %d: %.2f\n", i, sum[i] / count[i]
}
}'
avg 1: 0.12
avg 2: 0.14
avg 3: 0.13
avg 4: 0.17
avg 5: 0.17
```
The winner is clearly `head | tail`, but this isn't as useful since we want to print filenames and line numbers too, to sed it is!
previously, the script used:
```bash
awk 'NR>='"$start_line"' && NR<='"$end_line"' {print NR ":" $0}' "$filename" 2>/dev/null
```
now it uss:
```bash
sed "$start_line,$end_line"'!d;=' "$filename" | sed 'N;s/\n/:/' | sed "s|^|$filename:|"
```